It is hard to know based on one game that didn't matter, against special teams players, but I am surprised that they were willing to take this little in return. I don't see there being a QB controversy. Maye is clearly the guy. Apparently, the Patriots and the rest of the league are basing their assessment of him more on what they saw in college than what they saw in that one game. But my question is, if that is all you are getting back, why do the trade?
A 7th round pick in my mind has no value at all, so that part doesn't worry me at all, who cares. You can get the same player as a undrafted FA as you can in the 7th Round (more or less). I guess this turns out to net to be about a 6th round pick. Not sure the Patriots will do better than Joe Milton even with the 5th round pick straight up, even discounting that it is costing you a 7th round pick too.
Maybe it is easier to use a 5th round pick to move up in the draft than to use Milton directly and/or a 7th round pick, that is the only thing I can think of.