We haven’t exactly thrown a lot of quality prospects Keefes way. Lil is okay, but honestly on a mediocre D core like this he’s hard to shelter. He didn’t work out with any partner really last season. Timmins isn’t great either don’t get me wrong, but he’s the placeholder until Jani is ready to go
No A level prospects, but we went through a bunch of promising B prospects that never seemed to reach the level needed to supplement our core. You can argue that we traded young promising prospects away in some of our trades (Muzzin trade in particular), but I do think we didn't do great in terms of developing the following young players in Keefe's tenure:
Dermott, Sandin, Liljegren, Robertson, Holmberg, Barabonov, Johnsson, Kapanen, and Moore.
Most teams have a number of players that surprise and become solid NHLers during a 5 year span. I don't think we have any outside of Knies who really hasn't had too much time to develop with the Leafs yet (last year he also played on the 4th line at times which probably isn't a great development move)
I'll defend Keefe and Dubas more than the average poster as I think, despite some warts and growing pains, they're both above average coach/GM that were ultimately let down by our core forwards lackluster playoff production. However, this was my biggest issue during Keefe's tenure... we could've really used some secondary talent that turned out better than expected (see Hyman; pre-Keefe for recent example).