Not sure why you've got such an issue with this to be honest. I'd suggest, over the years, that Milner has played a significant role in our seasons, to one extent or another. Milner has now gone, Delph has now arrived. So now Delph will play a significant role. Yes, he's not the English version of Messi, but neither was Milner. He'll work his arse off, he'll pass the ball fairly well but not spectacularly, he'll get more than enough game time to make a "significant impact". He's not an "instead of Pogba" signing, he's a replacement for Milner.
What I just don't get is people thinking every single signing we make needs to be a £40m world class player. No squad, not even Barca or Real, is made up of 25 world class players. It's not possible to keep them all happy, and it's not affordable. Delph, a good quality player, a full England international, a player who at £8m is costing at most 50% of what he's actually worth, he ticks so many boxes it's unreal. Comparisons to Sinclair are just remarkably ill informed. The vast majority of City fans saw no sense in the Sinclair signing, he never demonstrated being good enough, even in a rotation role, for City. Delph is definitely good enough to play his part. He's certainly on a par with the likes of Fernando and Milner.