Yeah, anything above 100 million is absurd for Isak. He's a good player, but not that good. Wirtz is a generational prospect - I think we'll see evidence of that season. He's the Kaka, KDB, Iniesta of this generation, and I absolutely endorse paying whatever it gets for a player like that, especially since he's only 22. We either get him for two contract terms (8+ years), or we get to sell him again in 3-4 years time, again for a big fee.
Isak on the other hand is 26, and has some injury history. How do we justify a 100+ million outlay on a player like that by any of the recruitment principles FSG claim to swear by? At 26, you'll have him for another 5 years at best, he won't have any resale value, and I really doubt that he's SO transformational a player that he'd guarantee another couple of PL title and/or CL titles. That's the only way that kind of expenditure is worth it tbh given that you'll never recoup resale money for him.
Another way to look at this - over a 5 year contract, how many goals do we see Isak scoring? In 3 years for Newcastle, he has 109 appearances and 62 goals. So he has availability concerns, and he's not THAT prolific tbh. We're paying 120 million for a player who'll score 100 goals for us in 5 years? Those are going to be some pretty expensive goals...
