If you really believe he has a strong arm, Its hard to believe that you've actually watch any games he's played in and that's okay. He isn't even the most mobile QB, either. His whole game is about mechanics & footwork, good decision throws, and what seems like a good understanding of defensive schemes (at least at the college level). If you watch any Cam Ward games, you can clearly see the athleticism, off-schedule throws/trick plays, and arm strength, but he definitely isn't as "nimble" in the pocket or calculated as Sanders. Win or lose, Sanders plays with what seems to be more visible urgency and technicality than Cam, and I think that's something that will make him a better pro than having a big arm with raw talent.
If you have the time, I strongly suggest watching the CU vs CState game in 23'. Great game and a good showcase of Sanders' strengths and weaknesses. Also, that was the game Dallin Holker played himself into the NFL.