By MARK SIMON

With free agency just underway, you’ve probably looked over the rankings list and made judgements on players. Perhaps you’re using Wins Above Replacement to get a snapshot of a player’s overall value. But it’s human baseball-fan nature to place a priority on how good the player is as a hitter in assessing his overall value

With that in mind, let’s look at things a little differently. Let’s examine the defensive value of 10 free agents – five premier free agents (star players) and five premier defenders.

Premier Free Agents

J.T. Realmuto, C

What are we supposed to make of Realmuto catching 4-of-19 (21%) runners stealing in 36 games, a year after nailing potential baserunners at a 43% clip in 2019?

How you answer that question answers what you think of Realmuto’s defense as a whole, as his numbers are largely driven by the stolen base stats. Realmuto had 10 Stolen Base Runs Saved in 2019 after totaling 4 such Runs Saved in his four previous seasons combined. His track record as a pitch-framer is average to below-average. He’s had two good seasons blocking pitches but he’s also had three full seasons in which he rated average.

George Springer, OF

Springer is going to get paid for the total package. He’s a good center fielder by the numbers, maybe not Kevin Kiermaier or Byron Buxton, but still decidedly above average. Over the last two seasons he’s averaged just under 15 Runs Saved per 1,000 innings, within striking distance of Kiermaier’s 16.5 and in the top-third among center fielders overall.

Springer can also play right field if needed. Some stories link Springer to Boston, which makes sense given his Connecticut roots. He’s also an outfielder used to playing quirky field dimensions in Houston, which may make him a good candidate to adapt well to Fenway Park.

Marcell Ozuna, OF

Premature wall climbs and other odd plays aside, Ozuna is probably going to come out a little better than he looks. In his three seasons playing left field full time (2017 to 2019 for the Marlins and Cardinals), he totaled 13 Runs Saved. When Ozuna played well, his arm helped him along (he has 11 career Outfield Arm Runs Saved).

If your team signs Ozuna, we’ll guess that he’ll likely be a DH, but don’t shudder if he has to play the field.

Marcus Semien, SS

If Semien had been a free agent after the 2019 season, he’d have been poised for a huge deal after posting his best offensive season and his second straight season with at least 10 Runs Saved. But in 2020, Semien struggled at the plate and in the field with a .679 OPS and -5 Runs Saved.

The biggest concern for Semien is his arm. As you can see in the chart below: From 2016 to 2020, Semien ranks second to Andrelton Simmons among shortstops in Runs Saved from Range but ranks tied for next-to-last ahead of only Xander Bogaerts in Runs Saved from Throwing.

Seems like he’ll need a good first baseman (like a Matt Olson) to maximize his value.

DJ LeMahieu, INF

LeMahieu is 32, a time when infielders often decline considerably in defensive value. The good news for him though is that there’s a track record of success, though his best seasons, 2017 and 2018, are a few years removed. LeMahieu has shown a little bit of a dip in performance in that his rate of making mistakes (what we call Defensive Misplays) is up. He’s had 16 in about 850 innings the last two seasons, compared to the 12 he had in over 1,100 innings in 2018.

LeMahieu’s versatility is important to note too. He comes out average statistically at both first base and third base, where he could move if he is determined to have lost some of his skill.

Premier Defenders

Andrelton Simmons, SS

Simmons’ track record is that of an all-time great. He’s the leader among shortstops in Runs Saved since we began tallying the stat in 2003. The concern is in the recent injuries that have shortened his last two seasons.

The -2 Runs Saved in 2020 presents an interesting thought exercise for teams, which can be articulated by this arbitrary-endpoint based stat.

In 2020, Simmons made 3 plays on ground balls with an out probability of 34% or less. He failed to make plays on 8 plays on ground balls with an out probability of 66% or higher.

In 2018 and 2019 combined, he had a near-even split between the two (38 vs 40).

I watched the 8 ground balls that dinged his numbers the most this year and said to myself “when he’s right, he makes that play” for almost all of them.

So it’s a matter of Simmons doing what he needs to do to get himself right moving forward.

Yadier Molina, C

No Yadi, there was no conspiracy against you to keep you from winning a Gold Glove. Just a few catchers whose numbers were better than yours (especially Tucker Barnhart and Jacob Stallings).

Molina is still elite when it comes to stolen base prevention (he allowed 6 steals against 5 caught stealing and 1 pickoff in 2020) and he’s an above-average pitch blocker. Where Molina doesn’t match up with top catchers is in pitch framing. In 2019 and 2020, he graded out as average. His last above-average season was 2017.

We’d take Molina on our team every time, but a realistic assessment of his defense would be that he’s just plain good. Which is great for a 38-year-old.

Kiké Hernández, 2B and Kolten Wong, 2B

Hernández and Wong are arguably the two best defensive second basemen in baseball right now. Wong has won three straight Fielding Bible Awards there but Hernández could make a case that he’s better given that over the last two seasons he’s played nearly 800 fewer innings there than Wong, but only trails him in Runs Saved, 24-21.

Wong’s value is in his consistency. He’s reached a level of excellence in getting to ground balls that he’s maintained for three seasons.

Hernandez has enhanced value in a utility role. He has a positive Runs Saved total at each of the three outfield spots, as well as shortstop.

In each case, defense is extremely important to their overall value. Each posted an OPS below .700 last season, so their ability to field is a big part of what warrants their being in the lineup.

Jackie Bradley Jr. CF

Bradley had a bounceback season in 2020 both with his bat, where he cut back on how often he pulled the ball and added hits without sacrificing power, and in the field, where he saved 5 runs and tied Kevin Kiermaier for the lead among center fielders with 11 Good Fielding Plays (he had 3 Misplays & Errors to Kiermaier’s 8).

On his best day, Bradley is a top-end defensive center fielder who adds value with his bat and arm. He came out as average defensively in 2018 and 2019, so the key for him will be getting to balls (like the one below) and making great throws as he ages beyond his prime.