The trade market likely has something to do with that, what with those Nolan Arenado and Kris Bryant rumors a-swirling. Also playing a role is the possibility that teams are hesitant to commit nine figures — Donaldson’s likely going rate — to a player who not long ago turned 34. Really, though, teams with near- to mid-term designs on contention shouldn’t be balking over committing to Donaldson. That’s because, age aside, he’s shown sustainable skills with the bat and the glove, and he figures to be major difference-maker in 2020 and probably beyond. 
As for Donaldson, in 2019 Donaldson had a wOBA of .377, which ranked 27th out of 135 qualifiers. In terms of xwOBA, however, Donaldson checks in with a mark of .387, which placed in the top four percent of MLB. As good as he was last season, the underlying performance may have been even better. That bodes well for 2020. 
As for Donaldson’s work afield, he also graded out quite well last season. Earlier in his career, Donaldson was steadily in the discussion for top defensive third baseman in baseball. In 2017 and 2018, however, injuries to his calf and throwing shoulder limited him to just a total of 165 games played across those two seasons and surely affected him in the field (and at the plate). Knowing nothing else, it’s highly encouraging that Donaldson was able to play in 155 games last season and spend almost 1,300 innings in the field. Best of all, though, Donaldson reestablished himself as one of the top fielders at the hot corner. To wit: 

  • Last season, Donaldson’s average exit velocity of 92.9 mph ranked in the top ten percent of MLB.
  • His hard-hit percentage of 50.0 ranked in the top three percent of MLB.
  • He had a “barrel” rate of 15.7 percent, which ranked in the top four percent of MLB. 
  • Based on quality of contact, Donaldson in 2019 had an expected slugging percentage of .536, which is higher than his actual mark of .521. 

After the headline-grabbing deals earlier in the offseason involving names like Gerrit Cole, Anthony Rendon, and Stephen Strasburg, it’s easy to think of a holdout like Donaldson as some sort of consolation afterthought. Don’t do that. Everything about Donaldson suggests he’s going to remain an elite performer for some time. 
Were this either of the prior two winters, we wouldn’t think much of Josh Donaldson’s ongoing availability. Those offseasons of course unfolded at such a glacial pace that it suggested malice aforethought. The current one, though, has been far more active, with most of the major names pairing with new employers fairly early. However, the free agent third baseman Donaldson at this writing remains unsigned.  Broadly, nothing predicts future health like health in the most recent season, and Donaldson as noted was healthy in 2019. Donaldson over his career has also been quite durable when not playing his home games on the taxing Rogers Centre artificial turf (and even then he was quite healthy over his first two seasons in Toronto). 
It’s easy to get hung up on a player’s age, especially when said age starts with a “3.” Donaldson, however, reminds us that it’s mostly about skill retention, and in 2019 he proved he still has a broad and elite set of skills. He carries no guarantees, of course, but everything suggests he’s going to remain a top-tier performer in 2020, and even if decline begins to set it in on balance he figures to be a valuable performer over the life of any contract he signs. 

  • Over at Baseball-Reference, Donaldson in 2019 ranks second only to Matt Chapman of the Athletics in terms of Defensive WAR. 
  • At FanGraphs, Donaldson ranks second among third baseman last season in Defensive Runs Saved. 
  • MLB’s Outs Above Average, which takes into account things like positioning during infield overshifts, ranks Donaldson for 2019 behind just Arenado and Chapman among primary third basemen. 

All of that brings us back to xwOBA, which is an estimation of what a hitter’s wOBA should be based on things like exit velocity off the bat and launch angle (Donaldson has long boasted a near ideal launch angle). xwOBA attempts to strip away luck — bad or good — and defensive play from wOBA and identify a hitter’s baseline skill. It’s useful for getting an idea of how a hitter figures to perform in the near-term future. Basically, if a hitter’s xwOBA is significantly lower than his wOBA, he’s probably going to come back to earth at some point. On the other side of things, if a hitter’s xwOBA is quite a bit higher than his wOBA, then better days are likely ahead.
Public-facing defensive metrics aren’t perfect, but when they all say the same thing — i.e., Donaldson is excellent —  and that squares with established reputation, then it’s safe to trust the numbers. This also passes the eye test, as healthy Donaldson boasts quick hands, excellent footwork, good instincts to his left and right, and a powerful throwing arm. That doesn’t figure to change, at least on the front end of whatever contract he winds up signing.  First, let’s take the bat. Last season, Donaldson in his first and thus far only campaign with the Braves batted .259/.379/.521, which was good for an OPS+ of 127. He also smacked 37 home runs and 33 doubles in 155 games. Yes, SunTrust Park is a hitter’s Eden, and the 2019 regular season baseball was indeed a jumpy one. Even so, Donaldson stood out among his peers for his quality of contact. Consider: 
Now let’s turn to an advanced metric called expected weighted on-base average (xwOBA). xwOBA grows out of wOBA, which assigns proper value to every possible offensive event that happens while a batter is at the plate. Those proper valuations of singles, doubles, homers, walks, etc., distinguish wOBA from more traditional measures like AVG, OBP, and SLG. Also, for simplicity wOBA is scaled to look like OBP, which means that, say, .400 is elite and .290 is pretty poor.