It's easy to point at last year's stats. It's easy to say there's no room. It's easy to say that age has caught up with him. But isn't that a lot to say for one season?
Before last season, Izzy rang up 8 consecutive seasons of sub 4 ERA, with 6 of those being sub 3. He averaged slightly under 1 K/IP, a solid WHIP, and held his BAA to .200 or better. If he's healthy, at worst he provides the Rays with another late inning option and insurance to Percy.
If the Rays can work out some sort of arrangment to keep Izzy in a DL stint/extended spring training to get some more work in and also see if any injuries come up, that would be the best solution.
Hammel looks more and more like a AAAA player and Niemann might get his final chance to prove himself (whether in a Rays uniform or elsewhere) but Cormier has had a very solid spring. For the first part of the season, giving Niemann a chance in the rotation with Cormier in long relief sounds good. Two weeks from now the Rays will be faced with another decision with Izzy, if he agrees to extended ST. Hopefully with time it works itself out as it usually does. But if Percy were to go down, or another relief pitcher--it's worth it to the Rays to take every opportunity possible to see if Izzy could be a fit.