Go back and look at the Yankees broken down starting pitchers over the past 15 years. They sign expensive FA pitchers and they usually wind up on the DL/IL. Same goes for the FAs the Dodgers have signed. That's why the Dodgers shifted their focus to developing talent through the minors or acquiring young talent when Friedman arrived. Look at the Dodgers lineup today:

Developed in the farm system: Pederson, Bellinger, Seager, Beaty, Barnes, Kershaw
Acquired as non-regular fringe prospect: Taylor
Acquired as a minor league FA: Muncy, Turner

Rich Hill is a good example of what happens when you sign a veteran FA pitcher for a big contract. Even if they're good, they're often on the IL.