Byrd, the Cubs' biggest free-agent move this offseason, batted .295 during his three seasons with Jaramillo as his hitting coach in Texas, and developed some power with 20 home runs and 95 runs batted in last season.
"We got him three years ago, and he was struggling," Jaramillo said Wednesday. "But as he got better and made adjustments, I saw that he could hit the set-up man, then I saw he could hit the closer, then I saw he could hit the No. 1 and No. 2 pitcher. A lot of guys can hit [Nos.] 3, 4 and 5, but when you're good, when you can hit the 1 and 2, that's something Marlon showed, and he kept improving and had an even better year [last] year."
Byrd's arrival means Kosuke Fukudome can slide over to right field, his strongest position defensively.
"He's a good kid, tough player and I look forward to having him on the team," Cubs manager Lou Piniella said.
Jaramillo said Byrd will have an impact in the clubhouse as well.
"He's a real positive type person," Jaramillo said. "He was big in our clubhouse, but he was big on the field. Being big in the clubhouse is one thing, but you have to go between the lines and get it done, and Marlon got it done."