Harry's Game there is no doubt McCabe has made some god awful decisions but you have been overly harsh there I reckon:
"Not spending in the JTW in the prem"
We did. We just let Warnock spend it.
"Appointing Blackwell full time"
After the nadir of the Robson appointment Blackwell came in and turned us from relegation dogfighters to actually being in the play offs in play on the last day of the season, within about 16 weeks. He really can't be blamed for giving Blackwell the job on that basis.
"Handing Creswell a three year deal"
He backed the management team at the time.
"Not backing Speed"
As Speed was part of the management team under Blackwell it could said he had been backed. He also went off to Wales prior to the next transfer window so it's a moot point.
"Not sanctioning a back up signing for Ched"
Apart from Beattie, Hoskins and O'Halloran?
"Appointing Weir on the basis of a nice power point presentation"
Unlike Robson/Adams/Wilson the vast majority of fans seemed to be excited by the appointment of Weir. Only in hindsight did it go belly up.
As with your other examples, there are plenty of McCabe's prize winning cock ups out there without making some up as above.