Pen management is such a crapshoot when you have the arms the Jays have... they have 1 high end guy (im not gonna call him elite yet, but hes on the high end of the level below elite imo) maybe 3 debateably above average guys (Cimber, Mayza and Garcia) 50 feet of crap, and then the rest of them.
I think what you're getting at mostly is that rather than automatically pulling a guy when he's dealing out the pen, run him out again until he gets into trouble. Well, lots can go wrong with that too. At the end of the day, Charlie can only put a guy on the mound, it's up to the pitcher to get the job done. Some days it's hard to get the exact guy you want out there because of 100 different reasons and you have to go the someone that maybe isn't the perfect choice. Also, if a guy is cruising, maybe you still want to take him out at the end of the inning so he's available the next day if needed. Can't always just let guys go until they let a guy on base.
all of this is not to excuse Montoyo at all either, just saying that with the lack of swing and miss in the pen in general, some days are just gonna suck.