Boldin was limited in practice by an ankle injury. He warmed up for the game, felt good and expected to play, only to find all his gear had been removed from his locker.
"Nobody was man enough to come and tell me what was the situation," Boldin said.
Whisenhunt said he told Boldin shortly after the list of inactive players was submitted.
The coach gave the players Monday off and said Boldin's attitude "doesn't concern me at all."
"In fact, that is kind of what you like to see because he wants to play," Whisenhunt said. "I think we all know how tough and how competitive Anquan is. The fact that he was upset that he didn't play is what you would expect. I certainly have no issues with that whatsoever."
The three-time Pro Bowl receiver has seemed out of sorts much of the season, an attitude that probably stems from the team's failure to give him a contract extension, something he has said the Cardinals management had promised to do.
He said at the start of training camp that he was not going to address the contract issue this season. No one close to the organization has accused Boldin of letting his attitude affect his play. Teammates consider him one of the toughest and hardest working players on the roster.
But, often injured in his career, he has been slowed this season by a high right ankle sprain. The injury occurred in the team's victory over Houston in Game 3, and was aggravated when the ankle took a direct hit last week in Arizona's home loss to Carolina.
Boldin didn't practice last week until Friday, when he worked out on a limited basis. He had done the same the previous week and played. He said he felt good after warming up in Chicago.
"If I had made the decision, I would have been playing," Boldin said. "When I came back in, all of my stuff was out of my locker, so I didn't make the decision. I know I was [ready]. It wasn't the field or anything like that. That's the best I've felt in three weeks."
Whisenhunt said his decision not to play Boldin was based largely on the soft field conditions.
"The field was thick and loose, and the footing on it wasn't great," the coach said after the game. "We've seen guys slipping and falling in other games, and I was afraid he could easily turn his ankle on that field coming out of a break."
Whisenhunt said Monday that another reason for Boldin sitting was the absence of linebacker Gerald Hayes with a sore back. That moved Ali Highsmith, a fixture on special teams, to the starting linebacker spot, requiring further shifting of the roster.
"I know what Anquan has fought through the last two games, and he has gotten a little tired at the end," the coach said after the game. "We have a tough stretch coming up, and a couple of division games. I wanted to make sure he was ready to go."
This isn't the first time the ultra-competitive Boldin has complained publicly about not being on the field. He had a nationally televised shouting match with then-offensive coordinator Todd Haley on the sidelines because he wasn't in the game as Arizona marched to the winning touchdown against Philadelphia in last season's NFC championship game.