No idea how good he is now because he hasn't played, but when he was last on the field he was probably a low end/fringe starter. Definitely not better than 15 starting QBs. His record was abysmal (Blaine Gabbert did better with the same team), and he was benched twice due to poor play. He was good enough to be in the NFL and possibly start for the bottom 3-4 teams. That's about it. He had the Super Bowl run, but that was well in the rearview mirror. He was no longer as good as he once was. And a single hot streak to get to a Super Bowl is overrated anyways. The likes of Kerry Collins and Rex Grossman went to Super Bowls too. Or even Joe Flacco, the guy who beat Kaepernick and just got run out of Baltimore.
Now whether they colluded against him or simply decided it wasn't worth the headache for a top end backup/bottom end starter is a different story, but that the NFL settled instead of fight doesn't look good for them.
EDIT: I thought about a bit more to see what teams I think might be worth starting Kaepernick. I'm just going to assume he is the same player he was when he got blackballed. A big assumption, but let's go with it. I got three teams: Miami, Jacksonville, and Washington. Denver just got Flacco, so that's a no go, but he's pretty bad at this point so you could maybe make the argument there. Alex Smith is better than Kaepernick, but I don't expect to see him anytime soon or maybe ever so Washington makes the list. Everyone else has either a better QB, a young QB on a rookie deal with more upside, or has no chance to do anything right away and would be better off going with somebody in the draft. That fits with the 3-4 teams I guessed earlier.