The Burke answer is truly hilarious. Not saying he's been good, but not even remotely close to Fletcher and Nonis.
If we're only looking at the early parts of each GM's tenure, Burke was worse than JFJ and Nonis.
JFJ took over in 2003 and proceeded to load up the team for a run at the Cup. Then the lockout wiped out a year so there wasn't anything to judge him on. It wasn't until after the lockout that he started screwing up and his reputation went downhill. For a good 2 years though, he was looking pretty good. Maybe not great, but not that bad.
Nonis' approval rating was pretty high at the start of his tenure, getting the Leafs into the playoffs for the first time in a decade. He was viewed as the Midas man that came in and quickly cleaned up Burke's mess. Then Clarkson happened.
Burke came in the middle of the of the 08-09 season, so he couldn't really do much until the off-season. Once the off-season started:
- a deal for Kessel, which would have been much better in hindisight, falls apart due to a miscommunication over draft picks. Because fax machines jamming up and owners vetoing trades was so 10 years ago.
- Kubina gets traded for a package that is widely panned. I think too much gets over this trade, but it was not a popular move.
- Komisarek gets signed to a massive contract that he never lives up to. The Beauchemin signing offsets it somewhat though.
- Picks and prospects get traded to acquire the Leafs' 2nd round pick so that an offersheet can be made (or at least threatened) for Kessel.
- Offersheet is never made and instead picks which were greater than offersheet compensation are given up for a Kessel. Picks end up being very high, and this trade will be talked about for generations.
The rest of Burke's tenure was much better (I guess it would have been hard for it not to have been), but that off-season basically defined his time here and he wasn't able to overcome it.
The only one who could come close to starting out their GM tenure in such a bad way was Fletcher 2.0, but even that wasn't as bad.