Skarner was not properly compensated for the loss of the old runes system
The highest winrate page for Skarner under the old system was: AD Reds Scaling HP Yellows Scaling MR Blues 2 AD + 1 MS/AS Quints
Under the new system, he received 8 base AD. That means he is missing out on 4.5 attack damage at level 1. Yes, Hunter's Machete DID give him more attack speed than had before, but his shrines make that stat redundant. Thus, he attacks REALLY quickly, but does 4.5 less damage every auto than he should. For a full clear, that's about 400 damage less than he had before (about 15 autos per camp, six camps).
As always, I leave it to your discretion as to how this should be handled. I would really appreciate it if this could get in 7.24. I'd rather not have to go an entire holiday season with sluggish clears. Merry Christmas and have a grateful Thanksgiving! Thanks for making the new runes system enjoyable and rewarding for us theorycrafters out there!