Garbage time/fleeting is a very misleading way to put it. Over entire seasons Renney had a 2nd ranked PP and Krueger a 10th.
Eakin's took over and tried to implement the San Jose model and that PP dropped to 20th, and than 27th in his second year before he was fired. Nelson took over with ~45 games to go and had the Oilers as the 4th best PP in the league for better than 1/2 the year. That's neither fleeting, nor garbage time.
And this new staff comes in and tries to implement the same PP that worked for them in San Jose, but that didn't work for the Oilers the two years prior. Haven't adapted it at all.
Tbh, I'd take the way we have improved 5 on 5 this season over Kreugers PP in a heart beat. I think that is more sustainable stat and style of play.
PP's win games, but strong 5 on 5 wins championships, imo. Not that special teams are unimportant, just a referee can deny a special teams, but they cannot take away you dominating @ 5 on 5.