5 subs is stupid. 3 subs were far better. Now, you can replace half the outfield players, which basically means you can change tactics completely. It means more of the result is down to the manager. It also means there’s less need to prioritise which games are important, you can start with your best 11 every game, and just substitute later if the result allows it. It also benefits clubs with bigger budgets more, as they can afford having a higher quality bench.
The idea that it favors the clubs with higher budgets is not borne out by the statistics. The 4th & 5th subs on the going clubs are not so much better than the 4th & 5th subs on lesser clubs THAN the first three subs. Besides the amount of time they play (avg 10-12 minutes) does not give them much time to affect the game.
Big clubs were winning all the time before and they are winning all the time now.