Funny enough. I think both Keefe and Babcock were potentially wrong. And it all comes down to timing.
During the time that Babcock was coach we were a deeper team, largely due to our best players being on their ELCs. As a result, we had the depth behind them, to put them together more often and not be hurt by it
During Keefe's tenure here we have not been a very deep team, for the opposite reason. As a result, putting our best two players on the sand line has thinned out the lines even more than they need to be imo
I will say I am generally a supporter of going back to Matthews/Nylander and Tavares/Marner. I prefer the balance of lines 1 vs 2 this way better, I like that it forces to teams to defend hard mins against 2 lines, and I think it maximizes both Tavares and Nylander as their individual skill sets imo mesh better with Marner and Matthews respectively.