Not sure about how Williams played last season, but he's always been very solid for Swansea and he would probably start for every team in the league besides Spurs and maybe United. Unless he is a shadow of himself, then I don't see the need to replace him when you have Jagielka/Holgate and even Funes Mori when he finally gets back as back ups. They would be starters for Liverpool, Arsenal and maybe even City.
None of those other 10 attacking players are on Sigurdsson's level. And clearly not many of the other Playmakers in the league are, considering he is tied 1st with the most goals and assists of any midfielder since 2014/15.
Keep in mind, I say tied with 1st because he has an assist against Arsenal that isn't officially registered for some odd reason.
It wasn't too long ago that Giroud was starting every game for Arsenal, so having him for £20-30 million is nothing to be ashamed of. Rather him than Rooney upfront.
And as far as Sigurdsson goes, you're not overpaying for arguably the best Playmaker in the Premier League when his stats are better than players worth £60-80+ million.
You rarely see any of the other Playmakers in the league scoring goals or assisting like him with their strong foot compared to his ''weak'' foot. I don't know if Ozil has ever scored goals like that, or if he can cross the ball on his left like that.
Didn't Ozil get bought for £42.5 million or something? Wouldn't he be sold for £60-80 million even though he's the same age as Sigurdsson and has worse stats? I bet none of you would complain over paying £50 million for him.