Mo Williams is an All-Star with an asterisk. After being snubbed from the team, twice, he subbed into the lineup in '09 because of injuries and proceeded to do absolutely nothing. At the time, his exclusion was met with derision from Cavs fans who were up in arms about their league leading team receiving only one All-Star placement. So he got in.
Going into the playoffs that year, Williams and Delonte West were considered one of the better starting backcourts in basketball. Among major contenders, Rajon Rondo was considered too young, Jameer Nelson too injured, Derek Fisher too old. Williams and West were the way of the future. Then they played Orlando, and we saw them for what they were: streaky shooters that don't scare defenses, and liabilities in terms of their ability to guard fast players.
This year, Williams is still starting. He still has the ability to hit a series of clutch shots, as shown in the Cavalier's game one victory over the Celtics. But in the two losses, all you have to do to gauge Williams' performance is to look at the player he's been marking (Rondo): 19 assists in one game, and a triple-double in another.
What does this say about Williams? To me, it validates the snubbing that he received before being included on the All-Star bench. It speaks of why Milwaukee let him go, and now has better prospects at point than Williams might ever be. It speaks of why in clutch moments, Williams, the point guard, the floor general, the supposed second option on this team, gives the ball up to LeBron at the point, while Rondo still commands his teams attention and controls the ball.
I still believe that Williams and the Cavs can beat the Celtics in 6. I don't see any sort of consistency out of anything the Celtics have been doing all season. But when they play Orlando, who has a more healthy Nelson, Vince Carter, and Barnes/Redick off the bench? Tough.