Don't know that I'd call this entire receiver corp "very solid" or "solid" at this point. IMO, more appropriate adjectives would be "promising," and "encouraging" based on what we've gleaned from last season.
Matthews: was a late rounder - and although his production played a significant role in contributing to Kaepernick being a 2nd round selection, he was and somewhat continues to remain "unproven." However, what we've seen as far as his ability to get separation and to move the chains gives us more quantitative input to be hopeful in his development. I wonder if there was no urgency to draft a midround WR because of what our coaching staff has observed up close and personal.
Hartline: Considering he was lining up for most of the year with slugs named Leggadoodoo and Gafney, thereby drawing the attention of the #1 corners and often safeties, the fact that he nevertheless became a 1000 yd receiver speaks volumes to the assumption that with other viable aerial threats drawing attention away, he will be a force to be reckoned with. Incidentally, it also says a lot about your young promising QB who managed to turn Hartline into a receiving force.
Wallace: What can you say? We now have the equivalent of a receiving homerun hitter lining up for us! No one has caught more 30 yard bombs since 09 than him. And that includes having slugs like Leftwich and Batch occassionally tossing them. I believe he also ranks #2 in 20+yd receptions. What's not to be excited about?
Gibson: As a 3rd or possibly 4th option, he's a threat and will keep defenses honest. Although he played in more games than Amendola, his production was comparable and he's shown he can find the endzone. If we expect him to the #2 go-two guy, yeah, let's get depressed, but as a reliable #3 or #4, there's grounds for optimisim
Binns: crapshoot that could go either way but has shown more promise IMO than Moore ever did
Tyms: see Binn
Keller: Not a great blocker but he actually killed us on a few games. He's a respectable TE receiving threat - especially considering who was throwing at him (and I use "at" purposely). It's no coincidence that the jest lost more often with him injured than when healthy.
Sims: potential endzone threat .. but TBD
Clay: has shown positive signs so who knows
Tight ends: quantum leap 4ward over Fasana and Clay/Egnew (and who knows, whether he's awoken or not)/and the other 2012 TE slugs.
Bess: yeah, that's a head scratcher and IMO a loss considering his dependability. He needs to be replaced and especially since Swope wasn't taken, I've gotta believe that the Fins braintrust has a specific plan either involving someone now here or presently not on the roster.
Although we have signed a few encouraging UFA WRs, that's always a crapshoot despite harvesting Bess through that route .. I would have liked to have seen a WR drafted where that ridiculous CB was instead (hopefully he'll make me eat my words downroad)