I guess the one thing I'm not hearing here (maybe I missed it), is what they are doing with respect to cards that there is no reason they can't redeem? I mean if I was their independant 3rd party, I'd be grouping the redemptions into:
New - less than 6 months from production
Unproducable - hard signed type cards where the card stock has been "lost" etc.
No Signatures - player has not signed regularly, very low volumes, constantly misses, etc.
Auto's Available - player has had autos in subsequent products, we're just not getting enough to catch up on old while meeting new demand
So obviously on the unproducable, say so, attempt to replace with something equitable and stick by the fine print on the card. On the no signatures, this is where some review of who he is would be necessary, if it's Afinogenov, replace it, and never use the guy in another product (it's not worth the effort). If it's Gretzky etc then you have to spend some more time working on getting autos (and per other comments leverage your contracts with those people or the NHLPA and push).
But the big group, the most concerning one, is those where they get lots of stickers in and just keeping throwing them on the new product. Someone should be able to build a plan to get these out. I know the idea of saying no new Spezza autos until all redemptions are filled won't work (as you're next product will have no autos in it). But take the time to build a plan and say you're missing 60 players worth of sigs, only use 40 of those guys in the next few products, fill the backlog on the other 20, then switch. You'll still have plenty of autos in products and you'll be working on a gradual plan to fix the old situation without upsetting customers. I for one have no issue with no Spezza auto's in the next 2 sets if it means I get my redemptions.
Of course like everyone I have my biases, most being around the fact that the majority of the redemptions I care about (there's plenty that they can replace to their heart's content) are of players who I collect, and who have been in tonne's of products since. Including a 1/1 - are you going to tell me that in all the sticker's they've gotten in, they couldn't have put out one less of his cards out over the past year and used the sticker on it!
You don't hire a consultant to fix a problem, you hire them to fix it and make sure it doesn't happen again. At least that's what a good one does!