Uh, well first - I don't think anybody who isn't in a mental ward would argue that Cal's entire package (including recruiting) isn't great. Anybody who looks at his resume and thinks he's not great at his job is absolutely bonkers. I don't think that's a stance held by anyone but Louisville fans and drunken degenerates. But I repeat myself.
Instead, what some people erroneously argue is that he's not good at the X and Os component of coaching. That is stupid as well, but it's a claim that requires actually looking back at his past as well as the national landscape to debunk.
What he did at UMASS was nearly as good as Brad Steven's run, about on par with Gregg Marshall, and better than Shaka Smart's run. He made that historic (for a mid major) five year run with two high major offered players on his roster at any given time.
As for what he does now, only a handful of coaches are apples to apples to compare with him - for the last 6 years, he's blown everybody out of the water with on the court results except K, but most of those other guys also have vastly less talent.
So who else gets enough talent that we're still talking apples to apples? K has just as many five stars per roster. Self is right there. Roy and S. Miller are often close behind.
Cal has blown all of those guys' results out of the water, except for K, who has had comparable results (one more championship, but two fewer F4s). And K is also in the GOAT argument. Self and Roy are lock HOFers, and S. Miller may well get there some day, they bring AAs off the bench, yet they can't keep up with Cal at a big boy school.
As for the lesser talent guys - are there a few who could produce as good results as Cal if they had UK/Duke/Kansas level talent? It's entirely possible. We'll see Izzo give it a shot next year. Maybe Gregg Marshall? But the reality is, if you see what Cal has done with low-talent rosters, and you have even a modicum of basketball understanding, you'll see that only a few select coaches have the potential to outperform him (over the long run - if you try to make points based on individual games, you are a statistical idiot) with equal talent.
Cal is one of the two best recruiters in the game, and at worst a top 10 bench coach. No, there are not more than 9 other guys in D1 who could pull off that UMASS run.
So, for the millionth time, unless you think we can pull K away from Duke (who has just as many losses as we do with just as many burger boys), I have no idea where people think the upgrade is gonna come from.