MINNEAPOLIS -- On several occasions during a difficult 2014 season, Minnesota Vikings left tackle Matt Kalil hinted his surgically-repaired left knee was bothering him, either by limiting his ability to handle outside rushers or toying with his confidence as he stepped into pass sets. After talking with Kalil recently, Vikings coach Mike Zimmer sounded confident the tackle's issues are gone.

"He feels very healthy again, so that's a good sign," Zimmer said at the NFL owners meetings in Phoenix on Wednesday. "His knees were hurting a lot, bothering him, but he'll be important to our success, as well -- making sure that he plays good, which will allow us to play better."

Kalil's struggles were a frequent topic of conversation during the 2014 season, and things came to a head after a Nov. 23 loss to the Green Bay Packers, when the former first-round pick got into a brief altercation with a fan outside TCF Bank Stadium. Zimmer talked on different occasions last season about Kalil's need to put bad plays behind him, and toward the end of the season, the Vikings started to see Kalil improve. He was only credited with one sack after Week 11, according to Pro Football Focus, and gave up just two hurries during that time.

The guess here is the Vikings will pick up Kalil's fifth-year option in May, so they can have another year to decide whether he's worth a lucrative contract extension. If Kalil plays the way he did as a rookie, an eight-figure salary could be in his near future. The Vikings likely won't pay him, though, if they don't see some stability in 2015.

"He might play great 70 plays, and eight plays he's not very good at all," Zimmer said. "We have to make him more consistent. We have to get him to finish better. I'm encouraged with some of the things he talked to me about the other day."