Uneven gameplay on Solo Battles is mine, it also plays into what you're saying here. Your blockers will be dogshit but the computers is impenetrable and I'm talking about when I have Taylor, Suh, Randall, and Miller on the front. I literally got tackled three times today by an O-Line...pretty sure that's holding but "Not A Big Deal".
Then there's the play in the secondary. No matter what they suck, I can't even really get much better secondary players and they get beat by even non-elite players. I put them in press...burned. Zone...burned. Man to Man...burned. No matter the coaching adjustments either. Then even if I have them locked down, their WR runs back towards the QB while my secondary stand around picking their noses.
For some odd reason since the updates, I can't even come close to blocking their FGs anymore either. Even with Sanders it doesn't happen.
Frankly I think it's a ploy to get you to keep grabbing cards in hopes of just finding that one guy to better your team.