"Threw yesterday and did not feel good," said Snell, referencing his Sunday bullpen session.
Snell had an MRI on Monday morning that revealed no structural damage. Previously slated to pitch against the Yankees on Tuesday, he is expected to miss one start. If all goes well, he'll likely pitch again on the front end of the Rays' next homestand.
"It's just been fatigued for a little while," Snell said. "Talked to [manager Kevin] Cash. Talked to the training staff, [pitching coach] Kyle [Snyder], everybody. We did what we thought was best for me moving forward.
"I got an MRI, that was good. So I'm happy about that. Just, it's been going on for a little bit. So we felt like taking one start off and resting and having this long break would be the best thing for me moving forward."
Cash said both the team and Snell are taking the "smart" approach regarding the ace left-hander's health.
"I think if you go back throughout Blake's career, this is his biggest workload for a first half, and we're doing the smart thing and he's doing the right thing by shutting himself down," Cash said. "There's some inflammation in there.
"I think if you ask any pitcher right now, there's some inflammation in there, in their shoulder or elbow. But with Blake, we want to be smart with him and get him set up where he can get off and have another strong half."
Cash said he was "very confident" that Snell's ailment will be short-term.
"I'm hopeful that he's going to respond to some rest," Cash said. "Some treatment and he'll get back out on the mound and he'll miss one time through. We'll just kind of take it day to day."
Cash did not believe Snell should have missed pitching in the All-Star Game.
"No, not from my thought," Cash said. "I talked to Blake before the break. We talked and he had his normal bullpen session in talking to him. He felt 100 percent at the All-Star Game, which I think was obvious the way he threw the ball. ... So no concern whatsoever, so I just think we're doing the smart thing right now on the back end of this half starting."
Bill Chastain has covered the Rays for MLB.com since 2004.