I don't think Saka has been at a consistently high level this season. Not knocking him as there have been some great highs, but there's plenty of chat going back a few months about his level, and whether it was impacted by fitness, injury or both.
While I'd love Arteta to win the manager award, it's hard to look past the achievement of Emery this year in putting them squarely in the CL places (yet to be confirmed of course). They were a slightly above relegation/mid-table fodder club a couple of years ago. Outstanding work.