The OL is the focus of offensive predictions for most and with good reason. However, it's easy to forget all the other offensive positions that struggled last year (hint... all of them!).
If the OL wasn't so bad, I suspect most would be talking about the WRs. PSU returned a single starter in Lewis and he only had something like 19 career receptions heading into the season. Everyone else who saw significant time was playing for the first time. I think a bunch of those throws that Hack missed were actually on the WRs. Not all of them, but certainly some of them. Their down field blocking also left a lot to be desired at time.
TEs were pretty awful. James, despite being 6'7" 270, played like scared undersized freshman. He took a really hard shot early in the season, was banged up, and looked like a guy playing overly careful because he knew he was headed to the NFL. Carter seemed like he wasn't interested in blocking and dreaming of of 2012 when he was McGloin's go to receiver. Brenneman is the best all around TE and he was out. Gesicki was pretty much a WR and looked lost in the few instances he was asked to block.
RBs were equally bad. ZZ is a good back, but not the type of guy that can do anything without some room; plus he was hurt midseason. Belton simply isn't a RB IMO. Lynch's blocking was embarrassing for most of the season and likely the reason he didn't see more time until the very end of the season (along with ZZ's injury). His running was pretty good, but those last few games were his real first experience as the lead back.
Hack... Hard to put too much on him considering what he was working with, but he had a pretty rough season. Add in the fact that EVERYONE was playing their first season in a new system and it's hard not to expect some improvement on that fact alone.
Coaching... Similar to Hack, it's hard to know how much was on them and how much was just being limited. That said, I think there was a bunch of room for improvement from the staff, specifically Donovan. I mean, how many times can you get stuffed with the wildcat before you realize it's not working?
The lack of slants and hurry up are other areas I think they will look back on and wish they did more of. Either way, they were in a tough spot and were still learning what they had. I think they clearly thought they had better blocking TE's (aka. H-Backs) than they really did, which threw a big wrench into an already rusty and broken running game.
Long post short, the OL is focus, but each and every other position last year was either extremely inexperienced or struggled for lack of talent/depth. Everyone was learning a new system and the coaches were still learning their personnel. Even if the OL doesn't improvement, I have to expect the improvement from Hack, the TEs, RBs (even though the depth is inexperienced), WRs, and Donovan.