You can see the logic in what he did (if you can't put a new player on with 15mins to go whilst 2-0 up at home when can you?). If we'd have put Barry on for Lennon then it would have been telling West Ham that we weren't going to bother trying to get out of our half anymore, yes you could argue in hindsight that his decisions were wrong, but you could also argue that the substitutions didn't actually change anything. Going down to 10 men killed us today. It took away all our options as we tired in the second half.
Bobby didn't make the tired mistakes, what more could he have done differently at the time?