The Bruins fell to the Sabres, 4-1, in Buffalo on Tuesday as the preseason rolls on. Oskar Steen scored late to prevent the shutout, putting home a rebound on Mason Lohrei’s shot. Kyle Keyser saved 20 of 22 shots through 30:25 of action before Michael DiPietro stopped 11 of 12 in 26:00 of relief.Again, the caveat to everything here is it’s still early. But here are three takeaways that I may or may not regret later…