Because of age, injury histories and other factors, the Rays are very protective when it comes to the number of innings thrown by their starting pitchers. And, ultimately, that’s a wise strategy. But too many quick exits puts too much pressure on a bullpen that always seems to be out of breath. The Rays had to use another six relievers in a blowout Friday night.Carrying 13 pitchers limits Tampa Bay’s flexibility in the field. And carrying two lefthanded, first base/DH types limits the Rays even more. With Matt Duffy likely to come off the Injured List in the next few days, and with Brandon Lowe not far behind, it’s hard to imagine the Rays carrying both Nate Lowe and Ji-Man Choi much longer.It was bound to happen, but it was still unnerving to see Brendan McKay struggle as much as he did against the White Sox. His breaking pitches did not look sharp, and he did not get as many swing-and-misses as his first three appearances. The defense had a lot to do with his high pitch count and early exit, but it was a good reminder that he’s still just a couple of years off the Louisville campus. John Romano can be reached at email@example.com . Follow @romano_tbtimes.