Exactly! Nail on head! It annoys me that people make excuses non-stop for Soldado, saying firstly he's not suited to AVB's tactics, then he's not suited to Sherwood's tactics, now he's not suited to Poch's tactics. Okay, Kane didn't play under AVB, but under both Sherwood and Poch he's going from strength to strength in a variety of teams and formations. He always does well.
There are other players like Chadli, Lamela and Capoue that started off shaky but are growing and getting better. Soldado and Paulinho started off poorly, stayed poorly or got worse under Sherwood and are still at that level under Poch.
You can say they might be good in this system or that, but they've been poor in 3 different systems and under 3 different managers. I'm inclined to believe they're both just poor players. Or at least, poor when compared to the level of player you need to compete for the top 4.