How long the union will last remains unclear, as Castellanos is set to become a free agent at season's end. By all indications, the Cubs would like to have him back. For his sake, Castellanos has gone on the record saying how much he loves playing baseball for the Cubs and at Wrigley Field.
With that as context, it will of course come down to money. The Cubs didn't have much of that to spend last offseason, when their biggest splash was signing little-used infielder Daniel Descalso. They project to have more money to spend this winter, but how remains unclear.
So what kind of offers will Castellanos draw in free agency? Jon Morosi of Fox Sports and MLB Network weighed in on that topic in an interview on the McNeil & Parkins Show on Tuesday.
"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," Morosi said. "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-milliond 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. He's not going to be a great defender but still good. I think five times 20 (million), five times 21 (million) to me feels about right. I may even be light there. It may be six years. He's really done himself a lot of favors there in Chicago. I think five times 20 (million), that range is a very fair estimate there for Castellanos."
Listen to Morosi's full interview below.