The Chicago Cubs replaced Starlin Castro at shortstop earlier this year with rookie Addison Russell. Castro handled the demotion quite well. He ended up shifting over to second base and significantly contributed down the stretch as well as in the postseason.

But rumors are bound to focus more on Castro's future with the Cubs, especially with the presence of Javier Baez in Chicago.

There's only room for one of these infielders to play second base, assuming Kris Bryant stays at third base and doesn't make a permanent move to the outfield. That cannot yet be ruled out, however, because we never know what manager Joe Maddon is envisioning for next year and beyond.

So until more is known, trade rumors will more than likely focus on Castro because Baez is three years younger (22), plays better defense at both middle infield positions and showed much promise after being called up this season. Castro, 25, has already been in the MLB for six seasons and he hasn't been awfully consistent over the past three years. His defense (at least at shortstop) is also a glaring issue even with nearly 900 MLB games under his belt.

And with $37 million guaranteed over the next four seasons, the Cubs simply don't need to pay that high of a price when there's a younger (and potentially) better version of Castro ready for MLB action.

They don't need middle infield depth. They need starting pitching depth.

"The Cubs can't come out and say: We have no idea what we'll get out of Starlin Castro from one year to the next," writes Patrick Mooney of CSN Chicago.

"Theo Epstein says he would be fine with keeping this group of position players intact, but the president of baseball operations also knows the Cubs might have to trade hitters for a frontline pitcher."

The team will likely address that pitching void in free agency, but they'll still need more depth since the No. 4 and No. 5 starters won't provide anything but inconsistency from one start to the next. Trading Castro could add a decent back end starter, especially with a number of MLB clubs in need of middle infield help.

Castro's audition at second base perhaps piqued the interest of others throughout the league because he's no longer viewed as solely a shortstop, which is primarily where the concern about his defense was concentrated.

By accepting his fate, Castro made himself valuable with his success at second.

Epstein said the Cubs "expect great things" from Castro for "years to come." However, rumors indicated Castro was aggressively shopped prior to this year's trade deadline as Chicago was looking to add some starting pitching depth.

Sure, maybe the front office isn't actively seeking trade partners for Castro right now, but it's hard to believe they won't listen if other teams come calling once the offseason begins.

While that's merely speculation, it's still tough not to think about what Epstein and the front office are considering. There were issues with both Castro and Baez this year, but Maddon seemingly helped coach away the struggles, creating more value for each of them.

Take, for example, the strides Baez made this year as well. He didn't even make the team out of spring training after playing terrible baseball from last September to April, but when his time came in September after a good campaign in the minors, he significantly contributed to the Cubs down the stretch and in the postseason.

There's certainly a reason to keep both middle infielders, but then there's a whole new argument that leaps to the forefront with that scenario. What if Castro is the part-time player? Will the Cubs really pay someone over $9 million per season to come off the bench? What if Baez is the part-timer? Aren't the Cubs going to give him a chance to start to see what he's capable of?

Maddon said Baez is "definitely an everyday kind of player," so it's difficult to envision exactly what the Cubs are thinking. Baez is marketable in many ways as well, so there's always the possibility he's moved.

They could wait until spring training to see who wins the starting job on Opening Day. Or they could have their plan in mind right now and look to execute deals once the opportunity arises.

There's at least one thing we can confidently say: The Cubs are not trading Addison Russell.