Not really down on Baker, but not up on Baker either. He is not big enough or fast enough to create separation with athleticism on the outside, so it is all stop and start/change of direction stuff (route running) but Baker is not quick like Edelman. Those Baker clips are against 2nd and 3rd string DBs playing zone and contain. Against a starting NFL DB playing man, Baker's route running will never command a double team, so he is OK but not anything special. Additionally Baker's hands are not great - he dropped a ball or two in each of the preseason games.
Watch the clip above on his Go route on the left side (about half way into the clip) - there is no separation - Baker scares noone. Watch the 2nd preseason game where he is not fast enough to create much separation on his Go route against backups (not fast) and drops the pass, and gets bodied down the sideline (not strong or big) and again drops the pass. Baker is OK as a route runner but has shown no flashes. Has not shown to be a #1 or a #2. But Baker is not bad either, he is smooth and fluid, good in and out and with change of direction. Seems to be where he is supposed to be.
I can not tell you how much upside he has with his route running - I am not trained in those predictions. Does that make sense?