Richardson was pretty much a consensus top 5 pick coming out of the 2012 draft... I'd imagine most any team would be willing to give up a 20+ pick to get the guy who might be the best RB in the league 3 years down the road. Of the teams that might make the playoffs this year, the Packers (they've only invested a 2nd round pick in Lacy), Falcons (Steven Jackson's contract is mostly non guaranteed, even if it's kind of a dick move), Saints (Ingram needs to go), Rams (the other Richardson is average at best), 49ers (Gore is about to be done, no guarantees that Lattimore will be ready when it happens), Cardinals (Arians loves Mendenhall, though), and Giants (depending on the level of internal panic about Wilson) should have been at least interested enough to pursue talks about it... and that's just if the Browns want to stick to the NFC! The fact that a player went for significantly less than what he was worth a short 18 months ago and apparently without causing much of a stir around the rest of the league is troublesome.
If your scenario is true, that would either mean that the Browns GM made a mistake being too hasty to get rid of him by not calling around to other teams first, or he didn't think Richardson was worth more than what was offered. If I had to guess, it's probably the latter... but why?