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When you're talking about something as revered and tradition-bound as the home run and a drop in power production, each new development requires a corresponding pharmacological explanation.

I gained a telling insight into the phenomenon two weeks ago in a story about Bret Boone's giving up his comeback bid and deciding to retire. A few ESPN.com readers praised Boone as a "gamer" who provided some wonderful memories in Seattle. But the overwhelming majority questioned the legitimacy of his numbers based on the assumption that he used performance-enhancing drugs even though he never failed a drug test.

With Major League Baseball hitters averaging a homer every 34.77 at-bats (compared with one every 33.08 last season), this is the recurrent theme: Fans and assorted media members are conditioned to think each new fluctuation in offensive numbers is a product of hitters being off the juice. Never mind that we're now in the fifth year of MLB's drug policy. Or that pitchers have used steroids, too. Or that there's no reliable test for HGH, so some players might be still be using their favorite PED.

There's a school of thought that the Mitchell report fallout and the sudden realization that you can get pinched without a positive test might have scared a lot of players straight this winter. Although baseball's amphetamine ban is also fodder for conversation, one AL assistant general manager asks, "Wouldn't that be more important in August, when guys really drag and their bodies start to wear down from the long grind of the season?"

As we debate the impact of weather, the state of baseballs and the quality (or lack thereof) of bats, some players are bucking the trend. Ryan Ludwick, Carlos Quentin, Joe Crede and Nate McLouth are among the players who hit homers in bunches in April and May.

The 2008 season hasn't been as kind to several other prominent names. In this week's installment of "Starting 9," we look at players whose power numbers have declined appreciably in the first 2½ months. Eight of the nine are under age 30, and none has been the subject of steroid whispers. The only trait they share these days, it seems, is warning track power.

Prince Fielder (50 homers in 2007, 10 in 229 at-bats this year)

Pick a theory, and chances are someone has floated it to explain Fielder's early lack of thump.

Among the most prominent: (1) Prince is hitting fewer homers because of his new vegetarian diet; (2) he was miffed in spring training when the Brewers automatically renewed his contract, and he's been out of sync ever since; (3) opponents are pitching him more carefully after his 50-homer season, and he has grown frustrated by all those breaking pitches and fastballs out of the zone; (4) he's pressing to prove that he deserves a $10 million, Ryan Howard-caliber deal in salary arbitration next season.

The Brewers offered Fielder and teammate Ryan Braun multiyear contracts in the spring. Braun signed for eight years and $45 million, but Fielder, a Scott Boras client, turned down a long-term offer. This is how life works with Boras: Young players go year to year, and they reap the desired windfall if they continue to produce. If not, they run the risk of being unhappy campers.

For whatever reason, Fielder has been more withdrawn and less media-friendly this season. When he hit four homers in five games during Milwaukee's more recent homestand, some observers joked that he had either stumbled upon some miracle tofu or slipped in a few late-night runs to Jack in the Box. In light of Prince's mind-set these days, we suspect he wouldn't find much humor in that.

Victor Martinez (25 homers last year, no homers in 197 at-bats this season)

You know catchers are having a tough time finding their power strokes when Atlanta's Brian McCann (12 home runs) has one fewer homer than A.J. Pierzynski, Ramon Hernandez, Joe Mauer, Kenji Johjima, Pudge Rodriguez and Martinez combined.

Martinez is a principal culprit in a teamwide malaise for the Indians, who lack the speed and run-manufacturing ability to make up for their lack of dynamism. They're 19th in the majors in stolen bases, and they have a team total of four triples -- two fewer than San Francisco outfielder Fred Lewis.

Manager Eric Wedge recently chalked up Martinez's big fat home run "zero" to a hamstring injury he suffered against Chicago on Opening Day. That would help explain his .335 slugging percentage.

"He wasn't even driving the ball in batting practice on the days I saw him," one scout said.

Martinez told the Cleveland Plain Dealer he's not troubled by his power outage. "I always say God does things for a reason," he said. "If I'm not going to hit a homer the whole year, I'm going to make sure I go out there and give my best."

Martinez wasn't quite as sanguine in a recent game against the White Sox, when he flied out to center field and responded by putting his foot through a plastic bucket in the dugout.

Alex Rios (24 homers in 643 at-bats last year, three in 265 at-bats this season)

After hitting 17 homers in the first half last year and losing to Vladimir Guerrero in the final round of the Home Run Derby, Rios went deep only seven times after the All-Star break. He wouldn't be the only player to fall victim to the post-Derby malady known as "Bobby Abreu syndrome."

The Blue Jays attribute Rios' problems early this season to a change in approach and some mechanical issues. After being a selective hitter in April, Rios began chasing too many pitches and struck out a whopping 31 times in May. Fresh off signing a seven-year, guaranteed $64 million contract extension in April, he might be going outside his zone to justify the Jays' financial investment.

As a tall, lanky, long-armed guy who hits out of a pronounced crouch, Rios is also susceptible to minor swing flaws causing major problems. The latest glitch: He's been dipping his back shoulder, lifting his front shoulder and uppercutting too many pitches rather than driving through the ball.

Rios continues to crush balls in batting practice, so the Blue Jays suspect a power surge is inevitable in the next month or two. Matt Stairs and Vernon Wells are tied for the team home run lead with seven, so Rios isn't the only Jay who's due.

Delmon Young (13 homers last season, one in his first 240 at-bats this year)

The Twins knew they were getting more of a gap-to-gap hitter than a slugger when they acquired Young from Tampa Bay. But they weren't expecting Melky Cabrera Lite.

Young has shown signs of picking it up of late, with three doubles in a win over the Yankees and an honest-to-goodness home run against Mark Buehrle last week. But that .672 OPS isn't exactly swagger-worthy.

Young's approach helps explain his numbers. He's an inside-out swinger, a la Derek Jeter, and AL pitchers have learned they can elicit some awkward swings by pounding him on the inside half. Until Young shows an inclination to turn on that pitch and pull it, pitchers will keep busting him on the hands.

Young is also now part of an organization that went 19 years without a 30-homer man before Justin Morneau achieved the feat in 2006. Twins hitters are conditioned to using the entire field and doing the "little things" necessary to move runners, and maybe he has embraced that philosophy with a little too much gusto.

"The Twins teach, 'You don't have to hit it over the fence. A single drives in a runner from second. If you go up there and try to crush the ball and strike out, that's an unproductive out,'" said an AL front-office man. "If you look at that team, Morneau and [Jason] Kubel are the only two who go up there looking to take a whack at a pitch and hit it out of the park."

With 40 homers this season, the Twins are tied for last in the majors with Kansas City. But they've found a way to make do with speed and aggressive baserunning. They rank second in the majors in triples and sixth in the AL in stolen bases, and their run total (294) is within five of those of the Tigers and the Yankees. Minnesota is looking more like a Midwest version of the Angels every day.

Khalil Greene (five homers in 241 at-bats, .311 slugging percentage)

Greene hit 27 homers and knocked in 97 runs last year, but he finished with a woeful .291 on base percentage. In the name of self-improvement, he tinkered with a new batting stance in spring training.

Greene tried a more spread-out approach, which helped his balance and ability to adjust to different pitches but sapped him of his power. After going homer-less in April, he went back to his traditional approach and went deep five times in May.

Like all San Diego hitters, Greene is an occasional victim of the Petco Park psych-out effect. In his case, the impact is exacerbated because he's one of the most extreme fly ball hitters in the game.

"You don't want to make excuses and say, 'I would have done this if the ballpark was a different size,'" Greene said in late April. "But as a hitter, if you hit a ball 380 feet the other way and it's a fly out, that's hard to overcome.'"

The Padres could live without home runs from Greene if he were a more nuanced guy. But when you have 484 career strikeouts, 169 walks and a .307 on-base percentage, you don't have many ways to contribute offensively when you're not going deep.

B.J. Upton (24 home runs in 2007, five in 227 at-bats this year)

Upton homered once every 19.8 at bats last year; this year, he's going deep once every 44.8 at-bats. But when the Rays say they're not concerned or alarmed, it's with good reason. Upton ranks second in the American League in walks behind Oakland's Jack Cust, and he's third in on-base percentage. His doubles, runs scored and stolen bases also are up appreciably from last season.

"It's just that he has been pitched hard," Rays manager Joe Maddon said in an e-mail. "I don't know if he is seeing the same mistakes he saw last year. We like the idea that he's not expanding his zone, and believe the homers will show up as we get someone hot behind him."

With the exception of a two-game, five-strikeout binge against Boston earlier this month, Upton has done a good job staying within himself and not swinging for the fences. That will continue to be a challenge as he fills in at cleanup for Carlos Pena, who is on the disabled list with a finger injury.

Miguel Cabrera (34 homers last year, eight this season)

You could blame Cabrera's disappointing power on the adjustment from the National League to the American League, but the transition sure hasn't put a crimp in Josh Hamilton's production. And you could chalk it up to playing half his games at pitcher-friendly Comerica Park -- except that Dolphins Stadium, his old park, was even less conducive to home runs from 2005 through 2007.

So here's what we know: Cabrera is an extremely gifted young hitter who generated early comparisons to Albert Pujols and has numbers that match up with Hank Aaron's at a similar stage of their careers. After coming over from Florida with Dontrelle Willis in an eight-player blockbuster deal in December, Cabrera signed an eight-year, $152.3 million extension in March.

Maybe Tigers manager Jim Leyland is right and Cabrera was simply trying too hard out of the gate. But the continued focus on his conditioning raises questions about his maturity and commitment. Rather than rise above Detroit's sad start, he has let it drag him toward mediocrity -- at least in April and May.

"The guy has a special bat, but he's just so big and slow," one AL scout said. "Maybe it's not fair, but the first thing that enters your mind when you see a body like that is 'undisciplined.' It boils down to makeup. You never know what's going to happen when you get somebody from another organization and pay him big money like that."

Tigers hitting coach Lloyd McClendon isn't concerned in the least. He expects Cabrera's numbers to improve as he continues to get more comfortable with his new surroundings.

"He's just showing that he's human,'' McClendon said. "He's in a new league, and every night he has to learn new pitchers. And like most young kids, he's trying to live up to the hype. In the end, he's going to be fine. When all is said and done, I think he'll be right there at .300 with 30-32 homers and 120 RBIs.''

Carlos Beltran (averaging one home run every 39.2 at-bats after hitting a homer every 16.8 at-bats in 2007)

Beltran's placid exterior has created the impression that he's more comfortable being a complementary player than the classic leader type. But it's unfair to refer to him as "soft." Beltran has appeared in all 63 Mets games this season despite having undergone surgery on both knees in the offseason. That's a natural power sapper.

Nevertheless, Beltran's progression isn't what general manager Omar Minaya had in mind in exchange for his seven-year, $119 million investment. Beltran hit 41 homers two years ago, dipped to 33 last season and has six in 235 at-bats this season.

For what it's worth, Beltran posts his best career slugging percentage numbers in July and August when the weather heats up, so he might have an extended run in him. The Mets are less concerned about Beltran than about Carlos Delgado, whose waning bat speed and inability to handle the premium inside hard stuff are now a given.

"He'll show flashes," a National League official said of Delgado. "But for most of this season, it doesn't matter what you throw him. He can't hit it."

Robinson Cano (four home runs, or one per every 60 at-bats)

When Cano was hitting .151 in late April, Yankees hitting coach Kevin Long and scouts who followed the club insisted that he was a "rhythm and timing" hitter who would find his groove eventually. Now that he has raised his average to a more palatable .227, that appears to be the case.

So when will the power come? Judging from Cano's career portfolio, he should start depositing more balls into the seats in about a month or so.

In his first three big league seasons, Cano hit 13 homers in 751 at-bats in April, May and June. In July, August and September, he hit 35 long balls in 859 at-bats. It might be a stereotype that Latin players pick it up when the temperatures rise, but Cano, a native of the Dominican Republic, sure seems to embody it.

Jerry Crasnick covers baseball for ESPN.com. His book "License To Deal" was published by Rodale. Click here to order a copy. Jerry can be reached via e-mail.