I actually don't worry about Cierre's game vis-a-vis fumbling. When he first was going in for Armando, he was getting the QB killed by hardly ever figuring out who to block. I thought "My Lord, we're not going to be able to play this guy".
I believe finding that out about himself produced a very helpful humbling in him, and he really dedicated himself to passblitz pick-up. By season's end, I was very impressed by how good he had gotten with it. Kelly has remarked several times since how confident he now is in Cierre's blocking.
I stayed luke-warm on Cierre not due to blocking or fumbling, but because I didn't think [and still don't] that he hit the hole all the time, nor got what the defense was giving him. I know all about the very good statistics. They're very encouraging. But I remember something from my past fandom which is heretical in most's eyes, but was very impressive to the open-minded.
There came a time in Barry Sanders' career when his erraticness at taking what the defenses were giving him produced many drive-stoppers. Detroit's offense went from the most feared in football to mediocre. Sanders still ripped off a couple of stunners a game, but the rest of the dancing choked the offense. This phenomenon got the Detroit coaching staff thinking about changing the entire offense especially in the red zone where Sanders had become fairly ineffective. Ultimately his numbers dropped off, systems changed, coaches were fired, Detroit sunk into mediocrity.
This is meant to be only mildly related to our own situation. The point is that I hope that Cierre is more decisive this year and a little less "ambitious" at hitting home-runs. That's all I'm waiting for with Cierre. He's plenty capable of doing that. Because of his admirable accomplishments at blitz pick-up, I know that he's internally-motivated to get there. I still just need to see it, so I can exhale on this issue.
P.S. I'm a lot more concerned about Jonas holding onto the ball than Cierre. If he can't, then Cam or GAIII MUST play more that Coach thinks they're ready for.