Why do folks always throw out "name some examples".
Sometimes you blow a big play or two that makes your mistakes very visible.
Sometimes you make numerous small mistakes on plays that at the time don't seem significant. But as the game goes on, these mistakes may end up contibuting to long drives that do result in an opponent scoring.
Samuels errors, most of which are the latter, are very visible to me. Maybe because whenever I see an opponent make a big play, I see #26 lying on the ground behind them.
He takes bad angles on tackles. He tackles with his shoulders rather than wrapping up, he get's intimidated when tackling larger backs and WR's.
He's a very average at safety. Not horrible, as I've seen worse, but a tad overrated and I think his spot could be upgraded.