Another ace on trade block? Here are 5 fits

On Sunday night, responding to reports that Luis Castillo could be heading to the Yankees, Reds GM Nick Krall said: “[The rumors] are completely false. We intend to have [Castillo] as a member of our rotation for 2021.” This story was published a day before Krall made his statement.

The Hot Stove this offseason has been shaped way more by blockbuster trades than free-agent signings so far, including two massive starting-pitcher swaps involving Yu Darvish and Blake Snell. But if big things like these come in threes, is it possible one more giant-headline, star-pitcher trade -- and possibly the biggest of them all -- is still to come?

Last month’s report by MLB Network insider Jon Heyman that the Reds were discussing the possibility of trading either Luis Castillo or Sonny Gray was quickly overshadowed by the Darvish and Snell trades that unfurled days later. But a swap of either top-of-the-rotation arm by Cincinnati would prove just as momentous, particularly if it involves Castillo. Since he turned the corner for good in 2019, Castillo ranks 11th in FanGraphs pitching WAR and is tied for 14th in strikeout rate and tied for 15th in adjusted ERA+ among starters with at least 150 innings. And of particular interest to teams, the 28-year-old will only reportedly earn roughly $4 million this year as a first-time arbitration-eligible player -- and he is under club control through 2023.

Castillo is in his prime and affordable, so Cincinnati might just be putting out feelers rather than gearing up for a trade. But if the Reds are actually serious about moving Castillo, his trade market should draw just as much interest (and perhaps an even bigger return) than the sweepstakes we saw for Darvish and Snell. When looking at 2021’s Steamer projections via FanGraphs, Castillo is forecasted to be among baseball’s six best starters (about as valuable as Darvish and more valuable than Snell). Castillo is the same age as Snell, six years younger than Darvish, and again, on a cheaper contract than either of them.

But the most intriguing thing about Castillo is how good he is at both missing bats and getting ground balls, two skills in which pitchers are rarely elite at the same time. Consider that since the start of 2019 ...

• 110 starting pitchers generated at least 1,000 total swings and 350 balls in play from opposing hitters

• 20 of those 110 recorded elite whiff-per-swing rates of at least 30% in that span. A different group of 20 got ground balls at least 50% of the time

• Only two pitchers belonged to both groups of 20: Castillo (35% whiff, 57% ground-ball) and Stephen Strasburg (31% whiff, 51% ground-ball, almost exclusively from 2019)

• Across those two seasons, Castillo ranked third overall in both whiff rate and ground-ball rate

A starter of Castillo’s age and skill set doesn’t come on to the trading block all that often. If the Reds make him available, here’s a short list of five projected contenders that should seriously consider dipping into their prospect war chest. We looked at teams with perceived rotation holes whose farm systems were rated favorably in the most recent MLB Pipeline organizational rankings (and thus could seriously pique Cincinnati’s interest).

Yankees
There might be a little smoke here, as The Athletic's Jim Bowden reported Friday that the Yankees had been in touch with the Reds about Castillo, though he clarified that those discussions have died down recently. New York’s rotation has a whole lot of uncertainty behind Gerrit Cole, and now that DJ LeMahieu is reportedly coming back into the fold, the pinstripes can focus on addressing that. In fact, they already started by reportedly adding Corey Kluber.

Trading for a star like Castillo would certainly grab headlines back from the Mets, but it makes baseball sense, too. Castillo could hold down the Yankees’ No. 2 rotation slot while Luis Severino gets healthy and Deivi García and Clarke Schmidt round into form. The latter two prospects might be untouchable for a trade, but general manager Brian Cashman has more talented arms like Luis Gil, Yoendrys Gomez and Luis Medina, alongside potential change-of-scenery candidates in former Top 100 prospects Albert Abreu and Estevan Florial, that could help him put together a package.

Braves
A bullish read on the Braves’ rotation says Ian Anderson is for real, Kyle Wright found something at the end of 2020, Mike Soroka will return fully healthy and Charlie Morton still has plenty left in the tank. But the inverse might also hold true for each of those starters. While possibly a top-10 MLB rotation as is, Atlanta could use another sure bet like Castillo, who could age gracefully with Ronald Acuña Jr. and Ozzie Albies and also help the Braves make a push in Freddie Freeman’s last year before free agency. The Braves boast three Top 100 prospects, headlined by Cristian Pache (No. 10) and Drew Waters (No. 22), and they still have a farm system deep enough beyond those two to entice the Reds.

Twins
The White Sox have put the rest of the AL Central on notice, but it seems like the Twins haven’t really begun their offseason shopping yet. Minnesota could use some additions beyond the expected re-signing of Nelson Cruz, including for a rotation that looks thin behind Kenta Maeda and José Berríos. Perhaps the Twins could deem Trevor Larnach (MLB’s No. 77 prospect) a little more expendable with fellow outfielder Alex Kiriloff (No. 27) knocking on the big league door. Minnesota might need one splashy move up its sleeve to respond to Chicago’s big winter.

Blue Jays
It's been a close-but-no-cigar winter for a Blue Jays club that many felt would pull off the biggest moves, but there's still time to spend some of the prospect capital that team president Mark Shapiro and general manager Ross Atkins set aside for the Francisco Lindor derby. Toronto has a solid top two atop its rotation in Hyun Jin Ryu and Nate Pearson and good back-end depth in Robbie Ray, Tanner Roark and Ross Stripling, but another frontline arm like Castillo would really help this upstart club make some noise in the AL East. Despite callups for their brightest young stars in recent years, the Blue Jays still owned MLB Pipeline’s seventh-ranked farm system as of last September.

D-backs
The NL West got a whole lot more daunting given the Padres’ December spree, and with all indications that the D-backs are still looking to contend instead of rebuild, they’re going to have join the arms race. FanGraphs’ projections currently rank Arizona as MLB’s third-worst rotation, with Madison Bumgarner’s regression making Zac Gallen that group’s only above-average contributor on paper. Adding a premium arm in Castillo won’t fully close the gap with San Diego and Los Angeles, but it would be a start -- and the D-backs have a good supply of Top 100 prospects including outfielders Corbin Carroll (No. 85), Kristian Robinson (No. 30) and Alek Thomas (No. 45) and shortstop Geraldo Perdomo (No. 79). Recently graduated prospect catcher Daulton Varsho could also be put in a package.