Hi, hope you don't mind an obviously biased point of view from over here in the States...
It's simple. If you believe that results will tend to converge back to goal differential, never mind newer stats like xG, this is a good appointment. Not great, JM has some clear weaknesses, but much better than the results at Leeds indicate.
OTOH if you believe that managers have a sustainable power to take a side that concedes lots more goals than they score and still win a few more games -- call it Steve Cooper's magic power -- well then, obviously Jesse's a disaster.
I'm pretty squarely in the former camp (nationality aside, I just believe xG and GD help predict the future). On one day Leeds dominated Arsenal, missed a penalty, and lost 0-1... so their fans bemoan the lack of finishing. On other days, they would lose 4-3 to Tottenham, or even pull out a wild 4-3 comeback over Bournemouth... and the fans would lament that you can't stay up in the PL conceding two goals a game. You all are more familiar with the RB style than most, so you understand that when the results aren't happening, it looks completely shapeless and incompetent. But when the pressure works, you induce a Mendy howler to beat Chelsea 3-0, or a Gomez mistake to win at Anfield, and everyone says it's the other team losing rather than you winning.
TBH he's kind of stubborn about the Red Bull stuff and perhaps slow to moderate it when the defense is springing leaks. His Leipzig stint imploded quickly because the team felt they'd moved into a post-Ralph kind of RB fußball and that Jesse was moving them backwards. But at Leeds he never lost the team even with bad results.
Your side has decent xG stats and I expect you'll get a modest bounce. Likely not enough to stay up, but it's somewhat plausible. More likely, his tactics will work much better in the Championship because of opponents with less composure, so maybe in two years you'll be in a really good place.
