"Kind of a lingering toe issue that I felt the last game," Cobb said. "Talked to [head athletic trainer] Ron [Porterfield] and [manager Kevin] Cash and all those guys about it afterward, and monitored it. Saw that the next day it was still there a little bit and decided just to be smart with it. With the new 10-day [DL], it's nice [to miss] only miss a start."
Cobb allowed that it's "just something we'd like to get knocked out in August."
"So when you get down to that stretch in September, you can be 100 percent and feel good," Cobb said. "Feel strong. Hopefully get all of that going and feeling strong going into the playoffs."
Cobb is 9-8 with a 3.80 ERA in 23 starts this season.
"You're talking about a guy who has probably fought his mechanics more than anything coming back [from Tommy John surgery]," Cash said. "The last thing we want to do is let a lingering issue turn into something more. He's been on a really good run."
Snell is 0-6 with a 4.98 ERA in 14 starts with Tampa Bay this season. He received a no-decision in his most recent start Thursday at Houston, when he allowed three runs on seven hits in four innings. The Rays optioned Snell to Durham on Friday.
"The way I look at it, it's another opportunity for Blake to come in here and keep making progress and help us win games," Cash said. "So yes, he was the obvious choice [to make the start]."
Snell told reporters he was excited and "ready to go" for the start.
"Something to build on," Snell said.
• Matt Andriese (right hip stress reaction) threw three simulated innings on Tuesday and Cash said, "He looked great."
"Obviously we'll make sure he comes in feeling good tomorrow," Cash said. "He'll throw a bullpen. Then hopefully getting him started in a rehab game over the weekend."
• Kevin Kiermaier (right hip fracture) and Matt Duffy (recovery from Achilles surgery) stood in against Andriese, but Kiermaier did not take swings, though he did take swings earlier in the batting cage. The Rays' center fielder has been shut down for almost a week due to a back problem. Now, the outlook appears better.
"[Kiermaier] feels much better," Cash said. "We just have to be careful with K.K. -- he did have that five- or six-day break where we don't want him to ramp it up too quick. From a body standpoint, I think he feels fine. Now we have to get him back in a little bit more baseball shape, the gradual process of swinging, fielding, all those things."
Cash did rule out that Kiermaier would be back before the end of the current homestand, but did allow that Kiermaier might be ready by the time the team begins its series in Toronto on Monday.
"Potentially," Cash said. "Just have to see how he keeps making progress."
Fantasy spin | Fred Zinkie (@FredZinkieMLB)
While he lacks the swing-and-miss skills (5.9 K/9 rate in 2017) of an elite fantasy starter, Cobb has produced a 3.07 ERA and a 1.01 WHIP across his past 11 starts, and he should be stashed in virtually all leagues during an expected short stay on the disabled list. Shallow-league Cobb owners can check waivers for a replacement such as Hyun-Jin Ryu, Collin McHugh or Luis Castillo. Meanwhile, those in deeper leagues can take a look at R.A. Dickey, Brandon Woodruff or Trevor Cahill.
Bill Chastain has covered the Rays for MLB.com since 2005. This story was not subject to the approval of Major League Baseball or its clubs.