Pitching for the division rival Cincinnati Reds the last six seasons, Luis Castillo has developed into one of the best pitchers in all of baseball, and was going to be moved at the deadline to the highest bidder. Although it was a longshot that St. Louis would acquire a player of this level from a division foe, the Mariners made that conversation even easier after sending a large package to Cincinnati for the 29-year old.
The Mariners package included a top 20 prospect in all of baseball in Noelvi Marte as well as other highly regarded prospects to jumpstart the Reds rebuild. Castillo has not disappointed so far though, going 2-1 with a 2.70 ERA in 43.1 innings for the AL West contenders. Castillo is a huge reason the Mariners could go deep into October this year, something the club desperately needed due to their playoff drought.
Most talent evaluators would agree that Castillo is a better pitcher than Jordan Montgomery, but its hard to beat the value that St. Louis found. The only cost to the Cardinals was center fielder Harrison Bader, rather than a loaded prospect package that would have depleted their farm system. They have had to top the Reds package, meaning Jordan Walker is likely in the deal, which is not worth it for a year and a half of Castillo.
Based on player performance, the Cardinals would love to have Castillo on their staff with the likes of Montgomery, Wainwright, Mikolas, and Flaherty, but for the price point it would have cost, the Cardinals seemed to have made the right decision.