I've played with an m28 adaptive against two m28 adaptives on this map. In the early game it was easy to take map control with it as it pushed with me. The only thing I noticed is because of the map control it was more likely to starting eco'ing while the enemies struggling to try regain map control. This resulted in the illusion of it not doing much, but then it had an experimental before I'd got to that point.
From a map control perspective it took 8 mins for the game to be some what decided. I imagine it would be similar for you depending on what your gameplay style is. I guess perhaps you could explain what type of strategy your using on this map?
Other question, are you playing against aix m28's? That could explain why it feels like your team mate isn't doing much. I usually find once you go past 1.2 m28 becomes really difficult.