I know you don't like him, which is obviously your prerogative. However, if you're going to attempt to be objective in your analysis of whether he's good enough, i think you need to consider things better.
Pre Prison
As well as having a relegation season in the Championship where he was awful, but for reasons that weren't entirely his fault due to the role he was asked to play.
He also had a loan spell with Norwich in the Championship where he scored 10 in 28 games. Not prolific, but last season Billy scored 13 in 34 for United.
In League one, in a season where we didn't go up he scored 29 league goals, we know that Billy scored 30 in the promotion season.
Post Prison
Season with Chesterfield - 5 in 25, pretty poor return in a side that again got relegated. A season that was also plagued with Injury.
Last season Sheff United - pretty much injured all season, he unselfishly delayed his ankle op (carried over from the season with chesterfield) and then was recovering after this
This season Sheff United - He was clearly not fit or in form, hadn't played much in the previous season but had been fairly bright in preseason and then he was sent out to Fleetwood
This Season Fleetwood - Scored a decent number as i'd said above, doesn't mean that he's Championship level or ready yet, but it shows that he's bagging goals.
In summary, he was excellent and at his peak before prison, but since prison has failed to reach the heights of his pre prison peak in two seasons, but has physically not been fit enough to suggest that he is good enough.
However, the upside of this is that he's played more games already this season than last, we're not even at Christmas and he's 8 games away from reaching the 25 games he played for Chesterfield, having already returned more goals. For me the question mark remains on his fitness, but not really his ability
Subjectively, on pure football alone, the question has to be whether he is able to do a job for United this season in himself, in how he can fit the system and against the competition. He's 29, but looked leaner this season, so if he can get over the niggles, then it comes down to whether he's able to do the running that Billy, Leon and McG all do and recently Washington has shown. Washington has shown has the attributes in the last two games he's been involved and he's got plenty of pace.
essexblade73 offers a brief summary of last night, albeit on one viewing
For me, i think we're better to leave him where he is and look to bring that marquee striker in asap. If that doesn't happen and if Woodburn does go back then we have McG that slots in for Duffy and possibly Johnson... That might leave us short up top. So perhaps bring Ched back in as back up and hope he takes his chance when it comes.