Well I think the results for Marky are in at least. Nilly hasn't played in so long that I can't remember, lol.
Part of my issue with Clark at the time of hiring is that he had an old-boys club yes man attitude with Luongo and failed to rectify some of his shortcomings which were becoming very apparent especially for someone like me who has been a fan boy of Lu's since he came into the league.
However I can happily say that since he had no pre-existing relationship with Marky that I know of, he has definitely shored up parts of Marky's game and you can see the results on the ice if not so much in the save percentage column (IMO save percentage has a very significant team contribution to it).
He has worked on Marky catching the puck - like just catching it over and over. As a result, Marky's glove positioning is more square and forward (the last bit is the important one). As such he has been making many more glove saves and I can't remember him fumbling a glove-side shot in quite some time.
Marky had already improved his edgework last season, and Clark to my knowledge is not a super heavy movement pattern guy. But his down transitions and edges are even better than last year, which I thought were a significant improvement to begin with.
More importantly, I think Marky is more patient. He keeps his legs loaded instead of doing the leg shimmy which was very pronounced when he first arrived in Vancouver. Cloutier took that physical tell out of his game but Marky was still prone to being overly aggressive and attacking the game. Due to the faster and more lateral style of the game, this is not a consistent mental or tactical approach. This season we see Marky let the game come to him more. He picks his spots and holds his position longer, but he is able to improvise and employ his athleticism when the time comes. The change is so pronounced that I feel that we can easily attribute it to Clark's influence.
Another thing I notice is that Marky is general calmer and more even keeled. We see few outbursts from his this season. Although Clark does have a mental approach, he didn't do well at this with Luongo, who got calmer seemingly due to maturation (and long after Clark left). But whatever he is preaching has gotten to Marky.
It's ironic that I write this post after Marky gave up a goal due to poor post integration, but this is something that Clark is known for and despite that goal and one against Winnipeg I feel like Marky is less lazy (gets up more quickly and does not default to the down position as much) with his post integration work. A big idea of Clark's is that of having "dynamic" post integration and I think you can see that from the great pushes Marky is getting off his posts and the fact that he has been able to integrate the aforementioned glove hand improvements. Although he was beat the last couple of times by being "static", he has made many more saves than have beaten him because of the "dynamic" attitude to post integration that Clark has brought in his tutelage.
Finally, I see a lot of more old-school stick blade techniques used by Jakob. IMO this is a technique lacking in most modern goaltenders and has served Marky well so far this season. The league as a whole is resorting more to intentionally "hot" rebounds rather than the older smother technique, and stick redirection complements that perfectly IMO. The equipment and speed of players shots today means that contrary to the expectations of many fans it is not possible to "kill" or "control" rebounds on high quality shots. Stick redirection uses the momentum of the shot in the goalie's favour and is easier and more predictable than trying to deaden puck velocity so it falls at the goalie's feet as in the old days.
Overall I think the early returns on the Clark relationship with Marky at least have been very favourable, and I am excited to see what results the long term collaboration brings. This might also be good for Clark because Bob was such an unorthodox goalie with a lot of outside influences (kind of like Luongo actually), and so were the up and coming prospects in the Columbus organization. Marky has a really high ceiling IMO and is probably more receptive and easier to mould than those goalies Clark had in Columbus.