Mark Feinsand of MLB Network reported that "Castellanos' deal with the Reds has two opt-out clauses, after both the 2020 and 2021 seasons."
From 2013 to midway through 2019 with the Tigers, Castellanos played a combination of outfield, third base and designated hitter. At the plate, he hit .274/.324/.459 for 104 home runs and 424 RBI across 837 games.
After joining the Cubs last season, Castellanos' batting average improved from .273 to .321. In a 25-game span, he hit nine home runs, 16 RBI and accounted for 22 runs scored as well as 74 total bases with a .365 average and 1.112 OPS (h/t USA Today's Bob Nightengale). He took the field as an outfielder in all 51 of his Cubs appearances.
On Sept. 17, MLB Network's Jon Morosi previewed Castellanos' free agency to the McNeil & Parkins Show on 670 The Score:
"Castellanos, because of how young he is, the fact that he's a 27-year-old free agent, I think the way that he has played for the Cubs—the qualifying offer will go away by virtue of the trade—I think his value has probably doubled on a per-year basis almost in the last couple months. I really believe that.
"He could now be a $20-million-a-year player. I look at what J.D. Martinez got last time around (five-year, $110-million deal) and Nick is not quite as powerful as what J.D. was at the time, but he is younger. And I think his defensive value—he has a chance to still be good. ... I think five times 20 (million), that range is a very fair estimate there for Castellanos."
On Sept. 30, Cubs president of baseball operations Theo Epstein expressed a desire to keep Castellanos ahead of his free agency:
The Cubs, apparently, couldn't find a way to make a long-term marriage work.
Many teams whiffed when Detroit made Castellanos available at last season's trade deadline, but Cincinnati made sure not to make that mistake during Castellanos' free agency.
The Reds had a busy offseason. Third baseman Mike Moustakas became the largest free-agent signing in franchise history with a four-year, $64 million contract. The club also signed left-handed starter Wade Miley as well as 31-year-old outfielder Shogo Akiyama from Japan.
With Cincinnati, Castellanos figures to line up in right field alongside Akiyama in a reformed outfield.