Ok, so this is more of a quick rundown of available SP's rather than an in-depth analysis. I know, I know, "Dee Gordon ate all our munniez!" But if the rotation's going to get shored up, it's going to have to be via the FA market at least in SOME capacity. Here's the top tier of starters available.
Yu Darvish:
The top FA pitcher on the market, arguably even including Ohtani-san, Darvish comes with minor injury concerns (above and beyond those associated with >30 year old starts with a bajillion miles on their arms) to go with elite performance on the mound. He's been a solid 3.5-4.0 WAR pitcher when healthy, (he missed 2015 and half of 2016, but excelled to the tune of 2.7 FG WAR in 100 IP in 2016), he strikes out the world, and would be a genuine high-octane arm to pair with Paxton if the team wishes to pursue contention this year as their core's competitive window slowly, but surely, begins to close. His velocity has actually gone UP since his 2015 injury-related hiatus, with his fastball averaging 94.2 this year compared to his career average 93.1. He's as safe a bet as 30 year old TOR pitchers on the FA market ever get. Think $27mil x 6 years.
Jake Arrieta:
I know less of him than of Darvish, except to see that eye-popping 1.77 ERA on his stat-line from 2015, which helped power him to 7.7 WAR that season along with a well-deserved Cy Young award. He followed up that campaign with an impressive 3.8 FG WAR campaign, which slipped to 2.4 this last season as his fastball velocity declined each year following his peak of 94.6 in 2015, to 93.7 in 2016 and 92.1 in 2017. 'Pumpkin' is definitely on his pie chart of reasonably likely outcomes from here forward, but it's hard to argue that he's the #2 FA arm on the market and will get paid a similar annual salary to Darvish, with a couple years' less commitment being projected as necessary to land him. Think $25mil x 4 years.
Here's the second tier:
Alex Cobb
Think "Mike Leake's doppleganger" and you've got a good idea of what Cobb's about. A few more K's, a few more BB's, and a strikingl similar record of above-average value created has put Cobb in line for something like $15mil x 4 years on the open market. He wouldn't change the trajectory of the franchise, but he would shore up a rotation in desperate need of it given the number of question marks it contains.
Lance Lynn
Lancy Lynn will probably provide similar value to, albeit in a different fashion from, Mike Leake and Alex Cobb. A habitual 3+ WAR pitcher earlier in his career, Lynn's 2017 saw his output dip to 1.4 via FG as his K's dipped and both his BB's and HR's rose. Probably a safe-ish bet to Mike Leake his way through the league for a few more years, his latest season's performance dip probably brings him down a notch from Cobb's estimated cost: think $14mil x 3-4 years.
CC Sabathia
Sabathia's ace-hood is as far in the rearview as Felix' ace-hood. Contemporaries and cross-continent rivals for Best AL Pitcher year-in, year-out during their primes, both Felix and Sabathia are transitioning into Late Career Innings Eater types, and Sabathia appears to have adapated to the role reasonably well. In the last three years, he's tossed between 148-176 innings with FIP's 4.28-4.68 during that period. He's pretty much the definition of BOR innings eater at this point, and that's going to cost some team (probably the Yankees) $10-12mil/year for 2 years. He wouldn't be a flashy pick-up, but he'd add depth and steady performance in the rotation to a team that *could* be an offense-first unit going forward.
Below that tier are, really, reclamation projects (like Smyly & Pineda, who are in similar situations) or real long-shots (I can't even itemize them right now since I've been out of the loop so long; sorry). I don't know enough to comment beyond that, so I guess my question is: which of the above looks like the best bet to help propel the team into contention, both now and in a few years? It's easy to go with Darvish or Arrieta, but either one carries significant back-end risk, and at $25mil/year it's hard to justify that kind of risk.
Let's see what SSI's commenters think about this particular crop of FA starters :-)-