If he had become available earlier in the off season, so he could have attended OTAs and had more time learning the system, then I would have been more on board with signing him. If he is brought in now then he is behind his competition, and unlike other bottom of the roster guys, he is not eligible for the practice squad.
Baldwin would be on his third team in four years, and despite his once being a first-round draft pick, the fact of the matter is that in that time he has averaged just 15 receptions for 202 yards. While he is 6'4" and had great combine numbers, as a pro he has done nothing due to a combination of drops, poor routes, and apparently having an inability to pick up the playbook or make a commitment to being a professional football player.
The weakness in those latter areas would seem to make him a poor fit on a team that relies so very much on precise timing and positive mental strength as opposed to physical attributes to making the passing game succeed.