Wheeler and Harper have turned out to be bargains, at least thus far. You have disproved your own thesis, however, as both Wheeler and Harper were brought in at market price (actually, given the state and reputation of the Phillies at the time, very likely at a little above market price -- not as much above as Thome was, but likely above.) Yes, Arrietta and a host of RPs were disappointments. The cost of FA pitchers, like Wheeler, factor in the odds of flameout due to arm injury. Costly, even non-closer, relief pitchers are a notoriously fickle market, with more busts than among SP FAs. Given the lower injury rate, position players are less likely to be busts as big $ FAs, especially if you sign 28-29 year olds. The Phillies are proof that you can rise above .500 with heavy reliance upon FAs. I would feel very comfortable with the Phillies signing Correa. They've done well signing the best FA position player. To me, he's the best, the youngest FA middle IF and one who doesn't cost us comp picks and $.
In the end, I'll bring you around to my view. The Phillies haven't been harmed by over-spending on FAs. The Phillies have been absolutely murdered by their inability to sign and develop kids who become stars or even clearly plus major leaguers. That was our downfall, not FA. The Phillies didn't allow FAs to muscle aside promising prospects; rather, they signed FAs because they had incredibly few promising prospects. He never really accomplished anything in MLB, but Brown was the last prospect I thought was muscled aside for a FA and Young was a cheap FA.
And, yes, top tier FAs are priced at $10 million/WAR -- both because you can only have 9 players on the field so each successive WAR is worth more, but also because a 5 WAR star is a PR and sales magnet that a 1-2 WAR FA simply is not. Three 2 WAR players are going to bring the increased revenue that one 5 WAR FA will. That's what you need to sell season tickets. That may not be the strongest baseball argument, but it surely is a strong business argument. One might argue that three 2-WAR players spreads the risk of injury by diversifying investment, but the Phillies already have done that with multiple big-$ FAs.
For Andyb:
Even if one prefers Turner, based upon athleticism, I think Correa must be recognized as close enough to him that the lack of compensation more than makes up any perceived superiority of Turner.