Following Friday night's start by Wade Davis, the Rays' rotation will follow this order: Jeff Niemann, Alex Cobb, Jeremy Hellickson, David Price, James Shields and Davis.
"Part of our concerns are that Helly doesn't get too many innings and that Shields and Price are trending really high," Rays manager Joe Maddon said. "They're still going to be really high within their capabilities for the season. But the fact that [Cobb] has done so well, we thought that we could go with this right now and it benefits everybody.
"So by doing it, hopefully we're not losing anything. We're still going to try and pop James and David in on regular rest on occasions against the appropriate teams. But primarily it was to limit Hellickson and also to put a little bit of a break on Shields and Price."
Maddon said life of the six-man rotation is "finite" and will probabaly run its course by the middle of August. Cobb's success has enabled the Rays to take this route.
"We could not do it without [Cobb] pitching as well as he has," Maddon said. "He's done great and it's that simple. It's a great concept and other teams would love to be able to do that. But as far as doing that and still believing that you remain competitive, and he permits that to happen."