Id be interested in knowing how many of those games were blown in late August - October specifically since it seemed like the Cubs had a pretty lock down pen for a good 3 months but were heavily relying on Fulmer, Leiter, Merryweather, Alzolay, then Fulmer went down, Alzolay went down, Leiter completely tanked and the last 3 weeks of the season we had no horsefeathers idea who was going to get the outs needed to finish off a game (other that we knew Cuas was going to pitch almost every game). Was it because of overwork? Not sure but the pen was super thin beyond those 3 guys (and Ross's reluctance to try guys like Little down the stretch).
If the numbers are as I suspect (but could be wrong) this is still a problem that needs to be addressed. It's great that you can identify 3ish lockdown relievers from scraps but I imagine the lack of bullpen depth beyond those guys was a big factor in the late season slide and finishing 1 game out of a playoff spot. Would seem foolish to not make at least one decent investment in a reliever.
Edit: Just did some research: 7 of the 30 blown lead losses (23.3%) came in the final 22 games of the season (13.5% of the season). This doesn't include blown leads that we still managed to win of which there were a few in that stretch as well.