I'm not sure I'd have the balls to make the change, but there's certainly validity to your thoughts. Sydney we're able to expose Lever as 3rd tall as his strength is intercept, not 1 on 1 defending. Both Reid and Tippett are amongst the best contested markers in the game and Franklin is no mug, they're all also 196cm and above. Now you're not putting Lever on Franklin which leaves Lever undersized and outmatched against wither Tippett or Reid. The good thing is most of the ball gets funneled through Franklin anyway, but if Sydney suddenly smarten up and start isolating/targeting the Lever match up, we could be in trouble.
Taking Lever out certainly strengthens our ability to s**t down Sydneys talls, however you lost his intercept and 3rd man up ability, which provides support to Talia and Hartigan/Keath. We also lose some level of offensive drive as Keath, at present, is a long way off Lever(I think he will catch up to an extent though).
Last couple of Game Keath has done pretty well in Offense drive, and metre gained, if he is given the same role as lever I don't believe there would be a big drop, yes there will be a drop just not as big as some expect, on the flip side Lever defending one on one is starting to be exposed which is a worry come final times.
But I cannot see the Crows dropping Lever, unless he is going.