Probably Rosecrans to a pretty high extent? I'm not an expert on the campaign. But if part of the role of a commander is putting skilled officers where they need to be in order to do the most good, then that's a positive check in McClellan's column. Although I know Rosecrans complained about McClellan not providing him the support he needed.
Same with the blunders - you have to be in the right position to take advantage of blunders on the part of the enemy. While not making too many blunders yourself.
For the record, I'm not a McClellan stan by any stretch of the imagination.
I just like trying to see it from the perspective of the people alive at the time. If you're Lincoln, Cameron, et al and you're staring at a shattered army milling about Washington DC after a humiliating defeat, McClellan does make sense as the person to turn to. He'd provided victories when no one else could. He had real field experience. West Virginia was a major laurel for the entire Union war effort at that point and it was - seemingly - thanks to McClellan.
I suppose I'm going down a slightly different conversational path though. If the question is "did West Virginia provide McClellan with the field experience he needed to command the AoP and all Union armies or would he have benefited from more time at a lower level?" the answer is "he probably would have benefited from more field experience." I'm just saying they had no way of knowing that at the time, and when he was elevated to command he must have seemed extremely qualified. Enough for Lincoln to hold his nose about the whole slavery proclamation debacle McClellan had caused in West Virginia.