Editor's note: Now that free agency has started, Keith Law picks out possible best values, worst values and trade targets across every position group. He started with the catcher position Sunday, followed that with corner infielders, and now continues the annual series with a look at the middle infielders who have hit free agency, as well as some potential trade targets.

For the top 50 free agents across every position, click here.

Free agents (non-top 50)

Stephen Drew, SS: That's now a .185/.257/.347 line over the past two years for Drew, who can still play average defense at either middle-infield spot but hasn't shown even a whiff of competence at the plate since 2013. He'll turn 33 during spring training and probably will get a major league offer from someone -- there would be a bit of irony if it came from San Diego -- but at this point, he should be in a position in which he'd have to earn that roster spot by showing some offense at Triple-A.

Jimmy Rollins, SS: I was surprised at how badly Rollins played at shortstop in 2015, as it was the one skill he still clearly had remaining in 2014, by which point his offense was already starting to decay. His glove deteriorated to the point where playing Corey Seager there made sense for defensive as well as offensive reasons. My guess, given his age and apparent slowness in the field, is that he's finished, although I'd be willing to entertain a one-year deal for him to serve as a part-timer at short and perhaps second just to see if there's anything left.

Sean Rodriguez, IF/OF: Rodriguez is an interesting utility player who has played six positions in each of the past two years -- everything but pitcher, catcher and center field -- and, well, used to have some value with the bat before collapsing over the two seasons to a .228/.269/.403 line with 15 walks and 129 strikeouts. His impatience at the plate is a new phenomenon, contrary to what we normally see in players as they reach their late 20s or early 30s, and I would at least be willing to pay him a little more on the belief that the little bit of patience he showed earlier in his career might resurface in a new role.

Trade targets

Starlin Castro, SS/2B, and Javier Baez, SS/2B, Chicago Cubs (pictured above): The Cubs finally installed Addison Russell at shortstop late this summer, which should settle that position for several years but has created an obvious surplus at second base, with no clear place to send whichever of these two players doesn't get that job. Baez has the superstar upside thanks to his incredible bat speed, and he's a capable shortstop who could be plus defensively at second; Castro has the major league track record and the incredibly team-friendly contract. I'm sure the Cubs fear trading Baez only to see him become a 40-homer bat for someone else, but he still has so many issues with contact -- he was punched out in a third of his at-bats against right-handers in the majors in 2015 -- that trading him may be the right way to get the club another big arm for its rotation.

Marwin Gonzalez, SS, Houston Astros: Gonzalez has turned into a nice little player who gets negative attention because he has been surpassed by budding superstar Carlos Correa, leaving Marwin to handle utility-infielder duty barring a significant injury to Correa or Jose Altuve. Gonzalez can play either middle-infield spot -- he's fringe-average defensively at short but above-average at second base -- and has come into some power to go along with his high contact skills (and a very aggressive see-ball-hit-ball kind of approach at the plate).

Deven Marrero, SS, Boston Red Sox: Marrero has the defensive chops to be someone's everyday shortstop, where his bat will probably be a little above replacement level; he has hit a fairly empty .250-.260 across his minor league career and could do the same in the majors. He's hopelessly blocked in Boston and really should be part of a bigger deal for the Red Sox to land a starting pitcher, since he can go right into the shortstop spot and make the minimum salary for the next three years.

Neil Walker, 2B, Pittsburgh Pirates: If Jung Ho Kang comes back successfully from Chris Coghlan's assassination attempt, the Pirates can and should look to move Walker, who'll clear $10 million in arbitration this winter as a third-time-eligible player before becoming a free agent next fall. Walker turned 30 in September and is likely to be a 2-3 WAR player going forward, an average player in just about every aspect of his game but one who's too expensive for the Pirates given the presence of cheaper alternatives. They'll need to spend their money on other spots, like the rotation and possibly first base, rather than pay for duplication at second.

Jean Segura, SS, Milwaukee Brewers: The Brewers have prospect Orlando Arcia coming quickly -- he'll likely be ready to take over at shortstop by mid-2016 -- and have some choices to make around their middle infield depending on what they want to do with Segura, who is arbitration-eligible for the first time. Since appearing in the 2013 All-Star Game, Segura has hit .250/.282/.328 in more than 1,300 plate appearances with mediocre defense at short, so there's no question the Brewers will be better off with Arcia once he's ready. They could move Segura to second base, where he's likely to produce more value with his glove, and see if the switch to an easier position restarts his bat, or they could shop him now and probably take 50 cents on the dollar. They have Luis Sardinas ready to potentially fill the gap at short with platoon player Scooter Gennett at second, although they'd need to add another player to that mix if they move Segura this winter.

Eugenio Suarez, SS, Cincinnati Reds: Zack Cozart should be back at full strength in 2016, which means elite-level defense and no offense at all, but with the Reds likely to return the shortstop job to him, that should make Suarez, who hit well but with below-average defense in Cozart's absence, available. I saw Suarez as a prospect and thought he had the range to be an average defender at short, which he may still become in time, along with his 60 arm. He also has double-digit-homer power -- though perhaps not as many as the 21 long balls he hit across two levels this past year suggests -- and had solid walk rates in the minors, with plenty of bat speed to catch up to major league stuff. I like him as a project, someone a rebuilding team could plug in right away at shortstop and expect to develop into an average or better regular in time.