Joona Koppanen. | Photo by Maddie Meyer/Getty Images As both Bruins affiliates enter the home stretch, playoff positioning is on the line. It’s crunch time in the minors. Both Boston Bruins affiliates are primed for the postseason, with their remaining regular season games proving vital for playoff seeding purposes. After an up-and-down second half so far, the Providence Bruins seem to have rediscovered their identity at the right time, winning five straight games. That winning streak continued with three wins over the weeked. Providence dispatched the Syracuse Crunch (Tampa Bay Lightning), 4-2, on Friday before consecutive close victories over the Springfield Thunderbirds (St. Louis Blues), 4-1 on the road Saturday and 3-2 in a shootout at home on Sunday. As for Maine, after what has so far been a strong second half, the Mariners have been faltering as of late,…