You've said or implied that several times, but that's simply not true going forward. His contract was heavily backloaded, so he's owed over $100 million for his age 31-34 seasons (of an arm that has a ton of post-Tommy John innings on it) at an AAV of $26.5 million. That will make him the 11th highest-paid pitcher in baseball next season (https://www.spotrac.com/mlb/rankings/2021/salary/starting-pitcher/). The guys immediately behind him - Wheeler, Darvish, Cueto, Arrieta - are all either better than him, owed a lot less money long-term, or both. In any event, those guys were all signed to contracts with the expectation of being a #1 or #1a starter.
Corbin's good, but he's a lot less likely to be that good in 2024 when he'll be making $35 million as a 34 year old. That's a pretty serious time bomb in that contract.
Put it this way: if Corbin were a free agent this winter, could he get a contract for 4 years/106 million? Possibly, but I doubt he'd get more. Bumgarner is the same age with a reasonably similar track record in recent years and he didn't come anywhere close last winter.
Corbin repeated his breakout 2018 last year so he'd definitely get more than 4/$106M
Also, out of the guys you mentioned, cueto and arrieta are both trash at this point. Darvish is having a good start to 2020 this far but hasn't been inspiring in yeeeeeaaaars (plus only one season of 200 ip all the way back in '13). And wheeler had Tommy John and has a worse track record than corbin
