New England Patriots head coach Bill Belichick is at odds with Rob Gronkowski’s decision to train with Tom Brady’s controversial fitness guru.

According to the Boston Herald, Gronk has recently started working out at the TB12 Sports Therapy Center with Brady’s trainer, Alex Guerrero, instead of with the team’s trainers. And Belichick isn’t happy about it.

“At one point early last season, the Hoodie (Belichick) chastised Gronk in front of the players for being a TB12 client,” writes Karen Guregian of the Herald. “So maybe that was Belichick’s not-so-subtle way of trying to keep everyone from jumping ship on the team’s training staff.”

The problem that Belichick has with Guerrero was broken down by Hall of Fame tight end and Fox Sports personality Shannon Sharpe, who essentially called it a management issue.

“Gronk is trying to do what he thinks is best for him, but Mr. [Robert] Kraft is paying his training staff hundreds of millions of dollars a year,” Sharpe explained, adding that Gronk is looking for something more than just a trainer. “Why should anyone go elsewhere? I’ll tell you why. Because the greatest muscle an athlete has is his mind. It’s not his hamstring, it’s not his quad, it’s not his biceps, it’s his mind. They believe Guerrero gives them an advantage. He offers them something the Patriots training staff doesn’t.”