He shouldn't be playing through it. He should take 15. The team is playing like garbage and we need him stretch run.
I mean you
can play on a grade 1 strain, at that point it's mostly pain tolerance and handled through anti-inflammatories and icing anyway. But there's 3 months left in the season, the most important baseball to be played is far ahead of us, and you don't want to aggravate it any further and turn it into a grade 2 or a grade 3.
If it's grade 2, he'll assuredly be put on the 15-day DL, because he'll have to work to add strength back, much like Barrett is currently trying to do.
If it's grade 3, he's probably out for the season, because that's a full tear and that usually requires surgery (probably reattaching the tendon to the bone if it's a tendon issue)