JJ's speed-- or lack thereof-- isn't the issue, because having speed never has been a prerequisite for playing with Malkin.
The issue is that he needs a *****. Call it a puck retriever or whatever else you want, you need a guy who's got enough skill to play with and read off of what Geno (and Neal or whoever his finisher is) does but most importantly to be the guy who's always in good defensive position, goes to the net, and can win board battles/tie things up.
Fast or slow, big or little . . . doesn't really matter. But, Kule, Malone, Talbot . . . every one of them had that particular set of complementary talents.
And, really, here's why that is so important: You noted that what teams do to shut Sid and Geno down is to defend them in layers. More than anything else, Geno loathes giving up the puck and 'wasting' a shift.
When confronted with a layered defense, he's got three choices. Try to skate through three guys. Works once in a while but only when employed randomly. Try a slick pass. Same thing. Works once in a while but only when employed randomly.
The 'smart' thing is to dump the puck. But, I think from Geno's perspective, dumping the puck 'wastes' a shift when there's nobody but him that has any chance of getting it.
Go back to the 2009 finals. Watch what he did. If the layers attacked, he dumped and then supported Talbot on the chase. If the layers were loose, he'd take entry to the zone, force them to attack him in the offense zone, and use Talbot as an outlet whenever he got trapped.
But, you need SOMEONE doing that, and that just isn't JJ's game.
For Sid, he needs some speed and skill from ONE linemate because he and Kunitz, as a tandem, are better suited to utilize that type of player to attack the layers.
Fixing those two issues doesn't address the bottom six or the coaching. But, as I keep saying, if you put Sid and Geno in the best possible position to succeed and give both of them two complementary wingers each, then at least you give the Pens a fighting chance to overcome the internal obstacles.