Well he was shot by chewy and facing a pretty pissed off woman
I think you could tell she wasn't that skilled, ren even says she needs training. Think she was just really motivated by Han.
I know it's nitpicking, but two things... First, Ren may have been hurt, but he was apparently healthy enough to somehow get out of that facility, track Finn and Rey, and then circle around them to ambush them. Frankly, I don't know how he could've done that even if he hadn't been shot. Second, Rey had just been force slammed into a tree, fell 20 feet, and was unconscious for, what, a minute? I think it's debatable whether she or Ren was more banged up at that point. Certainly wasn't a huge advantage for Rey.
Sort of unrelated, but in thinking about that scene... what the **** was everyone doing there? So I guess Finn and Rey were heading to the Millennium Falcon, but if they were going in the right direction, where was Chewie? He shouldn't have been far behind them, he was somewhere between them and Ren. Somehow you had Rey and Finn heading towards the Falcon, Chewie behind them, and Ren behind him, but none of them saw each other until Ren had passed Chewie and ambushed Rey and Finn, and then Chewie avoided that fight and got to the Falcon? And on a planet sized base, the spot where they landed the Falcon, the shield facility, and the power oscillator thing, are all in such close proximity that all this could happen in 15 minutes? Am I crazy, or does that whole final battle just make no sense?