Yeah I don't get that either. Seen it a lot this post season from a couple different managers and it really is frustrating.
You put a big arm out there in a big game for a reason, and you gotta let him pitch out of jams! That's what they're there for! Especially with the way Lackey was pitching, besides Hollidays' shot, he was fooling a lot of the St. Louis at bats before he gave up that walk to Freese and a bloop single. Lackey may have given up a run or two that inning, but they were his runs to give up, he probably would have limited the damage, and he probably wouldn't have airmailed a throw to third either.
Reminded me of Scioscia and his over managing. When the guys in a zone let him stay out there and do his job. Especially when his replacement isn't an improvement!