Yeah, the two players dont have to be super similar - inflation is going to happen. That is the world. So if a dude is good enough, you may want to lock him up, get in before inflation. Even free-agents.
My theory on the matter is that every so-often a new contract comes and sets a completely new standard for contracts. Never down, always up. I remember discussing w/ people saying we shouldnt pay that much for Swayman (Bruins goalie) and I said, once you sign him to a 7m/yr contract, everyone is going to start getting them, and then it will continue to go north from there., Players dont have to get better for their contracts to age well. They just have to not crap the bed. And after Swayman signed (I think he was the third goalie to break the 7m/yr barrier) - like 3 more got that money in 1 year. Now he had an awful year, but the fact remains that there is a trickle up effect.
Soto would have never gotten so much money if Ohtani didnt. And now there is no going back. You want a top of the line stud? Who is proven. Already top 10 in the league. The bidding starts at 600m. Thats not coming back down. Pretty much, once Ohtani signed, everyone who was worth a damn became great value on their current deal (even Devers, assuming his SF stats arent his new normal) because Ohtani reset the market. And any contract signed prior to that became gold. Ask anybody who has ever said "Im going to wait for the price of houses to come back down before I buy (myself included)".
I always go back to Beltre. Everyone laughed when Beltre got 4 yrs at 16-18m. Two years later, everybody was trying to trade for that contract. Same player, its not like he broke out. If anything he had declined because this was after his tenure here so he was getting up there.
My point is that Roman doesnt have to be Betts for that contract to age well. Inflation will do the heavy lifting. He just needs to be adequate, and he'll be a steal in a few years. Because in a few years, todays top dollar will no longer be top dollar.