Doc, you're right, Vincent would most likely not leave his current organisation, unless:
1. The habs offered him way more money than he's currently earning and that Vincent was swayed by that
2. Vincent always wanted to work for the habs organisation
3. Vincent (perhaps correctly) determined that a coaching change at the NHL level will happen in Mtl sooner than in Winnipeg and that being in this org would give him the inside track as Julien's eventual replacement.
As for Lefebvre, he failed to develop players, when given a team of young players and also failed to win games when given many veteran and proven AHLers. Some players actually regressed under Lefebvre. Recently, Stephane Lebeau, who coached with Lefebvre, commented that they had a major philosophical disagreement on where the modern pro game was headed. Lefebvre advocated for old style hockey with defensive defensemen, while Lebeau favoured a faster pace, with more speed on the back end. We all know who was correct in their assessment.
Timmins on the other hand was crippled by the team constantly trading away picks. Sure he has some misses, but so do most other scouts. Also, it seems that certain GMs don't heed his advice. Recently, Timmins explained how he was forced to pick Louis Leblanc, while he actually would have chosen Chris Kreider. He also wanted John Carlsson the year before that, but Gainey traded the habs' first rounder that year to get Alex Tanguay. Here's the link:
http://blogues.lapresse.ca/lnh/2017/11/06/trevor-timmins-revait-a-john-carlson/
What has most plagued the habs, imho, is there atrocious choice of GMs, from Houle to Gainey to Gauthier to Bergevin with a brief respite of competence in Andre Savard. The asset management by those four GMs have wrecked the franchise and alienated fans.