CHICAGO -- It’s time, once again, to touch the third rail of Chicago Cubs baseball: The future of Starlin Castro.

There are few topics that illicit such a wide range of views than that of what the Cubs will ultimately do at shortstop as they head into their contending years. With the New York Mets in town this week, already the talk of a possible Cub/Mets deal has picked up again. The reasoning is simple: The Cubs have young hitting while the Mets have young pitching -- and each has a need for the other.

Are Starlin Castro's offensive skills enough to overcome his defensive deficiencies and keep him as the Cubs' long-term shortstop? Charles LeClaire/USA TODAY Sports

“We’ve had conversations with them,” Cubs general manager Jed Hoyer admitted Monday afternoon before the Cubs beat the Mets 4-3 that night. “We haven’t made a deal yet, but there have been matches that made sense and I’m sure we’ll talk to them in the future.”

What does this have to do with Castro? The Mets have been searching for an answer at shortstop, while everyone knows the Cubs are rich in middle infielders. Almost to the day they traded for Addison Russell last July, the media have been focused on a Cubs/Mets, Castro-for-pitching deal. But the Cubs have never shown any indication that one was forthcoming.

It should get attention this week again as the Mets will debut yet another young starter in 2010 first-round pick Noah Syndergaard on Tuesday night. Many fans will have Castro and Syndergaard switching teams by the end of the evening.

Syndergaard joins a group of young Mets pitchers that includes Jacob deGrom, Matt Harvey, Jon Niese and a recovering-from-injury Zack Wheeler. Should the Cubs move Castro for one of those young pitchers?

It all depends if you believe in Russell, because moving a three-time All-Star at age 25 can’t be a knee-jerk move. But in pure defensive terms, almost anyone within baseball will tell you they would rather have Russell over Castro from this day moving forward. Russell has a quickness about him that he’s only been able to flash a few times as he learns a new position in the big leagues, but he’s already polished at shortstop for a 21-year-old. He switches from glove to hand or from the ground to his feet as quick as anyone, according to scouts who have seen him play often.

Castro has made three All-Star teams mostly because of his offense. While flashy on defense, he doesn’t always make the smart or routine play. He’s vowed many times to improve in those areas and he has -- but not enough to warrant keeping Russell off that position for long. To be clear, Castro is a very good player, but we’re looking to max out on both players. And watching Russell at the plate, there’s nothing to say he won’t be a good to great offensive player over time. He has more pop than his smallish frame would indicate.

Addison Russell is not the hitter Starlin Castro is, but his defense would be an upgrade at shortstop. AP Photo/Gene J. Puskar

How do we know Russell will be better defensively? Even with improvement, Castro has been on the lower end of defensive shortstops in the game over the past five years. Maybe that’s all attributable to youth or maybe that’s what he is.

Errors don’t tell the whole story, but Castro has the most at shortstop since breaking into the league in 2010. He’s also played the fourth-most innings, but 126 miscues, including 52 throwing errors, are the most at that position. Having said that, his fielding percentage has improved over the years, though currently he’s 19th out of 28 this season.

Digging deeper, according to Fangraphs, going into Monday’s game he had minus-3 defensive runs saved this season, third worst among shortstops. Maybe he got one back with a diving catch Monday night, but he’s also third worst in that category since 2010. According to Baseball Info Solutions he has 11 Good Fielding Plays this season, which ranks sixth, but he has 17 Defensive Misplays and Errors, ranking him last. Over the course of his career he’s minus-67 in this category. All of that fits the eye test as well. Castro is prone to make the great play, but that doesn't hide the miscues on the more routine ones or decisions. Even he has admitted to his past problems in the field.

The bottom line is Castro isn’t close to being a Gold Glove defensive player, even though Cubs manager Joe Maddon challenged him to win one this season. Russell could be that guy. Can Russell hit like Castro? It’s doubtful, just because predicting a player to accomplish what Castro has at such a young age would be foolish. Still, you can see the potential in Russell at the plate. It’s not like he should be a .220 hitter. The Cubs will decide if the upgrade on defense -- and potentially in the pitching staff with a deal -- is worth the potential trade-off on offense.

Of course, there are no crystal balls. Castro could become a very good defensive shortstop or Russell could become a very good offensive player. Or if the Cubs really want Russell at shortstop, they could move Castro over to third base and Kris Bryant to the outfield.

There’s little doubt there is risk in trading Castro; he’s proved to be an All-Star while Russell is just getting started. But know this: The Cubs wouldn’t give up Russell in a deal for Cole Hamels, so we know how highly they think of him. And it’s for good reason. Nothing he has done since coming up to the major leagues has dissuaded anyone from thinking this is going to be a star player in the league for a long time. It could lead to Castro being moved, or even a position change, but the former still seems like the most likely scenario. And besides, the Cubs need the pitching.

“When you factor in the hitting and the pitching, people think it’s unusual, but it’ll happen at some point,” Hoyer said of a trade with the Mets.

He meant in the larger picture the teams are bound to make a deal, at some point in their existence, but that doesn’t mean it’s imminent. However, with Castro hitting well and the Mets employing a group of young starters, maybe it should be.