Variety of factors:
1) Well first it starts with Russ. Any competitor should tell you that. He needs to be sharper to start games and be the future HOF QB that he can be. That means overcoming impossible odds, not throwing balls high, etc.
2) The second is a complete lack of run game, which means defenses know to only focus on the pass. An incomplete pass leads to 2nd & 10, and a lot of long down and distances. Recipes for disaster.
3) The third is a complete lack of a game breaking receiving threat. A reliable throwing target that is almost always needed for a pass first offense. We don't have it, and we don't have the O-line to compensate for the absence of that target. Meaning Wilson has only 3-4 seconds to throw to a receiver that's most likely covered, and he's either sacked or scrambling by then
4) The fourth is simply scheme. Russell is a rhythm passer, but Bevell insists on constant long developing routes and there's really no flow to his playcalling. A great offensive coordinator would get Russell into a rhythm with short quick passes, use Jimmy Graham as a receiver to box out and get those 5-7 yard chunks. Get Baldwin frequently in space, using frequent motion so that Russ can better understand the coverage. Using more 2 RB sets with McKissic and Davis and giving Russ checkdowns when the deep option isn't there. Using more read options and QB options early to keep the defense on their toes early
All of these things could get Russell into a rhythm early and take off the pressure, where Russell is always trying to carry us on his back. So yes, Russ deserves some blame simply as a pure competitor. But we see how great he can be. He has all the tools. Sometimes I watch Qbs and I can say they have shortcomings but I truly feel Russ's greatest impediment is coaching and playcalling