It's a lot harder to shine at an inferior club than it is at a top one. There are exceptions of course but it's very hard to tell the true value of a player until they're surrounded by better talent, that's what helps unlocks a players true potential. No one would've imagined Dele to become one of the best players in Europe while he was at MK, likewise when Dier was playing for Sporting team, sometimes you need to take that risk on a player and put faith in them to come good when around the right talent. For me - and I genuinely mean this, no joking about for once - I think Jack Grealish would absolutely flourish under Poch's tutelage, Grealish himself supposedly said he'd make the England squad if he played for Spurs, I completely agree with him.
As for Seri, he's an excellent CM, mate, he just made a horrendous decision to join Fulham. Let's not forget, in the summer of 17 he was a couple of dotted I's away from being a Barcelona player. Granted, he never sealed the deal and got it over the line due to them signing Paulinho (

) but the sheer fact Barcelona were close to signing him surely tells you the calibre of player he is(?). Why he ended up at Fulham and not elsewhere I'll never know (seeing as us, City, Chelsea, Arsenal as well as Napoli all held an interest) but he is a very good player who's just being wasted in a very poor side. I'd happily sign him this January to add some quality at CM if Fulham were willing to sell although that's never happening.