Just my thoughts on this.
I think what's being missed here is that the 'old way' was not sustainable at all, we were taken over when we had almost a net zero on PSR for the rolling 3 year period up until then. We had almost £105m in clear headroom and then more the following January after the first.
It was the right approach 100% - use the headroom available to invest in quality players to get us out of the mire and up the table. It was a calculated gamble and it worked. I think no-one would disagree with the approach taken.
That said, what Mitchell needs to do differently to how we operated then to now is to work within the small amount of investment allowed each year in terms of net transfer spend - we get £35m p/a above breakeven only (£105m per 3 seasons rolling). This means we have now got to find more of the bargains out there if we want to keep our top players. If we're open to selling our top players for profit, it gives us much more room to manoeuver.
If we want to keep every single top player we have until they retire, all we get is £35m per season to spend above our breakeven point, assuming we break even. That's assuming we can cover all the wages of all of our players and all other club expenses on non-transfer-funded income alone. Our PL prize money and domestic cup competitions pretty much just covers us day-to-day.
We will increase this £35m effective spend by turning a profit through increasing income and minimising expenses and player sales. Champions League participation is absolutely massive. It gives us a massive injection in funds for the short term.
If we're currently PSR-compliant, the worst case scenario is we have approximately £100m to spend this summer (or whatever the sum total of the projected income received from CL participation is).
But.
If we spend that £100m on 2 superstars, with superstar wages, and we then don't qualify for CL the following season to help fund those wages without increasing our income outside of CL participation, we're potentially incurring losses as our wage-to-turnover goes south (Aston Villa) without the CL money retained for the following season.
You could say it's high-risk, high-reward, but I think it's a little irresponsible. We have a core of some fantastic, world-class players. I think what we need now is a quality squad, players bought for £10-£20m that can come in and do a job so we don't see the absolutely drop-off-a-cliff in quality when Longstaff, Willock or Wilson needs to play. The smart thing to do in my opinion is to buy up-and-comers so if they come good they either challenge for a first team place, or become a saleable asset to fuel the PSR-beating machine.
The other side is getting maximum bang for our buck on our deadwood. Mitchell's done well so far - Almiron and Kelly have gone for way more than I would have dreamed. Let's see how we progress.