He got the unfortunate luck of having to play in the city of washed up black quarterbacks.
Cunningham
Stewart
McNair
Banks
Wright
Heck, they wanted to draft Leftwich but got stuck with Boller after Jax selected him. There were rumors all over town that they were trying to bring him into town after he was cut. Then they cut Derek Anderson to keep Troy Smith. I realize Smith may not be "washed up", but we see the talent D Anderson has.

They cut Derek Anderson to make room for one of the entrants on your list, Kordell Stewart. It was after Boller got injured in the 2005 opener against the colts. They had to go to another entrant on your list, Anthony Wright as the starter, and didn't think Anderson was ready to be one hit away from being on the field as a rookie, so they brought in Kordell Stewart to back up Wright. They waived Anderson, hoping he would fall through and they could resign him to the practice squad but Phil Savage, who had been part of the Baltimore scouting/front office team that had identified him prior to taking over the Browns' front office earlier in the year, nabbed him off waivers. Troy Smith wasn't drafted until this year (two years after Anderson was drafted and lost).