There's a tendency when things are going badly to throw blanket criticism at everything, but the real problem with McInnes is his ability to judge a player and it's basically the main explanation for why we've regressed.
When we had Shinnie, McLean, peak McGinn/Hayes, etc. we were a legitimately good team. Any weaknesses McInnes has on the tactical side, with keeping players fit, motivating them and so on didn't stop us from having some level of success. What's happened is that despite having more resources to work with than most of the league, he's made countless bad signings and the quality of the squad has dropped. It's been an ill-conceived scattergun approach of throwing money at anyone with a reputation in Scotland rather than a considered building of the team.
The impression I get of him is that he completely lacks the capacity to judge players as they are and is always relying on third-hand rationales to make decisions (player X used to be good, player Y is about to be signed by Hibs, player Z scored against us once). It's not just about scouting - there's an abundance of information about players around now, what you need isn't extensive scouting networks of old guys in trilby hats covering the globe, it's good judgement about a player's potential. I watched just about every game Stevie May played for us, for instance, and to me he never genuinely looked up to it yet he got 60+ appearances because of who he was on paper. That tells me the problem is on McInnes judging players, not a lack of information about targets.
That's the problem and if we fixed it I don't think we'd be talking about passion or anything else.