I would agree, that would be his biggest fault.
But Lapo was not a bad coach. He was a rookie sure and a little high strung, but he certainly wasn't a dud.
I think had Mack found him better players (esp at QB), made some decent trades, and didn't meddle with the roster, Lapo's teams would've performed a lot better.
Lapo was a micromanager who coached the team too passively. Not a fan of that combination.