Some players really suffer under the wrong system. Soldado felt a bit like a cross between Defoe and Dele in style - as in a guy who could appear in the right places or playing in a more counter-attacking team, but under AVB we were a dull slow team that waited to play in front of the others, like Mousa Dembele personified (wanting to take on an entire team instead of just being quick and efficient). Under Tim he got ostracised. If he was in a Redknapp team, or a Mourinho team, I reckon he'd have been a 20-goal striker easily.
Defore was a bit unlucky in that he started off in an era that suited him, and then got swallowed by the 1-up-top style.
Under AVB, Soldado and Adebayor played a lot but Soldado wasn't scoring much, and that continued at start of Sherwood's 6 month reign before he gave Kane his first PL start with Kane scoring in his first 3 starts.
When Poch took over he again started Adebayor and Soldado in PL without much success, but Kane was started in EL where he started scoring. After about 2 months, Poch brought on Mason and Kane off the bench in a league cup home tie v Notts Forest that Spurs were losing. The 3 goals to turn the tie round came from Mason, Kane and Townsend (who had started) and within weeks Adebayor, Soldado, Kaboul and Capoue were toast being replaced by Kane, Mason, Bentaleb and a CB.
I think Soldado, who had been a top scorer in Spain, neither liked PL physicality nor did Spurs have the creative players to make loads of situations for him to finish - I think few PL teams did.

