I've been a huge Flacco fan during his entire tenure here and have defended him time and time again when his ability has been questioned. I maintain that he still could be a good quarterback when surrounded by a lot of elite talent with a supportive playcaller.
But I'm starting to look at things in a new light now, and chiefly because of two things: 1) ball security, and 2) decision-making. I simply can't abide a quarterback who is a persistent threat to turn the ball over at any time. I always called for the QB sneak in short yardage because it's the highest-percentage option, but after Joe fumbled on a routine sneak yesterday they probably shouldn't run that play anymore. He just can't hang onto the ball when hit.
He's also still making 5 or 6 terrible throws a game--the kind of throws that NFL QBs don't make. If you remember, he actually threw several near-picks in both the Cincinnati and New England games, the only difference is the DBs didn't quite make the play. Yesterday, he threw another one at the goal line, a horrible decision and throw that he needs to know not to do by now.
I just don't think he's improving in those areas. He's terribly inconsistent from game to game, quarter to quarter, and snap to snap. If he had an elite pass-blocking line and elite pass-catchers, he would surely look a lot better. I would love to see him play under a new coordinator. But I don't think any of those things will help the innate flaws Flacco had, flaws which I excused previously since any player has flaws in his game. I'm not sure if I want to excuse them anymore.