We weren't successful per se. We did well considering the points deduction. But, was we so successful it was worth turning down £1m for Leon Clarke? No, because like you say, we had an 'outside chance' of the playoffs. As a fan I was sorely disappointed losing him, but £1m for an ageing League 1 striker - who wanted to leave lets not forget - at the time wasn't a terrible deal. It finished our season for definite, but was likely to end up outside the playoffs either way.
I'd say our first season with MR was successful going into January, hence we secured most the targets we needed. We were always going to be outbid for McG, but at least we got Leon Clarke in at the time. Plus, resigning all the players we felt we needed to be successful. MR left, injuries, and we finished the season on a low point. Then Mowbray's first full season, again, successful going into January: no key players left the club, Maddison was sold and loaned back to us. Arguing his subsequent form was down to his transfer is illogical. The whole team was underperforming as we went from having a blistering season up to the New Year, to literally being one of the worse performing teams in the EFL...
I'm happy to agree with you about why we weren't successful in some of those seasons were unsuccessful... However, my main point is as followed: if we are successful this season going into January, we will retain this group of players, if not improve what we have...
With all said and done, I don't blame the cynicism we Cov fans have built up. The relationship with board and fan base is completely dysfunctional, most likely beyond repair and we simply treat our 'imperial overlords' (sisu) with mistrust and contempt. I know I do.