This FA has 2nd-highest WAR to Trout since '12

For each of Josh Donaldson's three full seasons with the Blue Jays, during which he won the 2015 American League Most Valuable Player Award, hit 111 homers and was the second most valuable position player in the game behind only Mike Trout, we were always viewing him with an eye toward the future. This offseason's free-agent class was supposed to be historically good, and Donaldson was a big part of that. It's not often that one of the game's best all-around superstars becomes available for all 30 clubs to bid on.
Well, Donaldson is a free agent, but little else has quite gone to plan. Beset by age, injury, contract extensions and tragedy, this year's free-agent group no longer looks quite so stellar, beyond the top three or four players. For his part, Donaldson has been on the disabled list four times in the past two years thanks to calf and shoulder issues, managing to get into only 52 games in 2018. When he was traded from Toronto to Cleveland, the return was a 27-year-old pitching prospect who'd put up a 5.32 ERA in the Minors in 2017 and missed all of this year due to elbow surgery.
When Donaldson did play this year, he hit .246/.352/.449, a decent line that's more similar to solid players like Mallex Smith or Kiké Hernández than it is in his usual position at the top of the hitting leaderboards. 
Donaldson turns 33 on Dec. 8, and his position on the free-agent market is now more "interesting" than it is "dominating." We saw how poorly some older players with injury histories fared on the market last winter; then again, none of them had the same track record of excellence that Donaldson does. So what is he? And which teams might find him worth the risk? Let's find out.

Two different Donaldsons in 2018
When looking at the season Donaldson just put up, we have to break it into two parts, separated not only by the distance between Toronto and Cleveland, but by the amount of time he missed in the middle of the season.
With the Blue Jays, Donaldson got into 12 games before missing a month with the shoulder, then returned to start for most of May before his tenure with them ended with the calf problem. It didn't go particularly well, and it wouldn't surprise anyone if he was playing through pain for at least part of the time. 
with Toronto
.234/.333/.423 in 159 PA, 105 wRC+, 28 percent strikeout rate, 89.7 mph exit velocity
After clearing waivers in August, Donaldson was traded to the Indians and made his debut on Sept. 11. He was only able to take 60 plate appearances over 16 games, so there's only so much we can take from the numbers, but he certainly looked a lot more like himself. 
with Cleveland
.280/.400/.520 in 60 PA, 149 wRC+, 17 percent strikeout rate, 91.2 mph exit velocity
The first thing you'll want to note there is the massive drop in Donaldson's strikeout rate, though again in a very limited sample. The second thing is the triple slash line, which looks nearly identical to the .284/.404/.549 (153 OPS+) in 2016 when he made the All-Star team and finished fourth in the AL MVP Award balloting. 

So that's promising, to be sure, and you can be sure that Donaldson's agents will be pointing that out while also pitching things like "over the past six years, he's been the most valuable infielder in the game," which is both true and not necessarily predictive in they way they'd like to have you believe. Teams aren't going to look at it that way, of course. Let's try to go a little deeper to see how they'll be approaching Donaldson.
What does the data say?
The underlying hitting numbers say something similar to the surface metrics, that Donaldson wasn't strong with Toronto this year, but looked much better after the trade. We like to use Expected wOBA, which accounts for both quality of contact (exit velocity, launch angle) as well as strikeouts and walks. The Major League average this year was .311.
Donaldson's Expected wOBA, 2015-18
2015: .389
2016: .408
2017: .396
2018 (Toronto): .306
2018 (Cleveland): .401
Let's go even deeper. While Donaldson's game was never really about elite level foot speed, since he's had such repeated problems with his calf, it's at least interesting to see what the data tells us, hoping that a change in speed might be a proxy for a change in skill. To do that, we look at Sprint Speed, the Statcast™ metric that measures foot speed in "feet per second, in a player's fastest one-second window." (Read more about how Sprint Speed works here.)
This is what we used early in the season to look at Matt Kemp's hot start and claims of better conditioning, which appeared to be true, and we can do the same for Donaldson. A Major League average Sprint Speed is 27 feet per second, elite is 30 feet per second and poor is 23 feet per second; in this case, we're more interested in Donaldson's trend than his ranking.
Donaldson's Sprint Speed from 2015-18
2015: 26.7 feet per second, 47th percentile
2016: 27.1 feet per second, 54th percentile 
2017: 26.4 feet per second, 49th percentile
2018: 25.4 feet per second, 21st percentile 
So that's a downward seasonal trend -- unsurprising, given the injuries -- and it's more interesting if we look at Donaldson's peak individual speed tracked on a month-by-month basis. Again, he was never a burner, but in 2015 and '16, his fastest single run per month was routinely and consistently in the 28 to 29 feet per second range. In '17, he started off slowly, which makes sense given that his calf flared up during Spring Training, before getting to his usual levels.
Donaldson only played in three months of 2018, obviously. But his peak September Sprint Speed of 26.4 feet per second, attained when he scored from first on a Melky Cabrera double on Sept. 19 against the White Sox, was his slowest monthly peak of the past four seasons.

That's worrisome, clearly. Then again, two days later, Donaldson indicated that worry about the calf was keeping him from running as hard as he's capable of, anyway.
"I've felt great with it," Donaldson said to MLB.com's Jordan Bastian. "The more positive reps that I can continue to gain, the more trust in that I'll continue to have. I haven't opened it up 100 percent yet on the basepaths, but I'm sure that'll come with time."
That can either be read as "the data is incomplete because he was capable of trying harder" or "the injury concern is real because even in September, he was being cautious." These are all factors that interested teams will have to consider.
What do the projections say?
It's tempting to just look at Donaldson's late-season performance with the Indians and assume that's what he'll continue being, but of course it doesn't work like that. You can't simply look at the 60 plate appearances you like and toss aside the 159 Blue Jays plate appearances that you don't, because it all counts. It's true that Donaldson's strikeout rate dropped with Cleveland, but it's also true that his 19 percent chase rate with them was wildly below anything he's put up before; his career mark is 25 percent, and it had never been below 24 percent.
Still, there's a few things we can look at which might serve us a little more effectively, starting with projections. Steamer, one of the most respected projection systems in the game, recently put out their 2019 numbers, which takes into account not only Donaldson's past history of excellence but also his age and missed time. 
Their numbers don't quite get Donaldson back to his AL MVP Award-winning peak, because no good projection system would. But they do look upon him favorably, as the third-best hitter among free agents behind Manny Machado and Bryce Harper.
2019 Steamer projection
.256/.366/.484 in 560 PA, 131 wRC+, 27 home runs, 4.5 Wins Above Replacement
That would have made Donaldson the eighth-most valuable third baseman in 2018. Also in his favor: the fact that because he was traded he was not eligible to receive a qualifying offer, plus the fact that the pool of available third basemen isn't deep. (The only other possible starting options are Adrián Beltré, who turns 40 in April, and Mike Moustakas, who is younger than Donaldson but has never been nearly as productive.)
Who might want him?
All of this means that the range of outcomes here are enormous. The high injury risk makes Donaldson appealing as a potential short-term, high-value type, but if enough teams see him that way, then someone is going to have to give him multiple years -- not five, certainly, but three seems reasonable. (For what it's worth, the readership of FanGraphs predicted a three-year, $58 million contract. That's not at all what we would have expected during Donaldson's Toronto peak, but seems reasonable today.)
For Donaldson's part, a one-year deal might not be appealing anyway, because then he might be headed out into next year's market a year older, possibly after declining a qualifying offer, into a third base market that could then include Nolan Arenado and Anthony Rendon.
"Overall," said a scout to MLB.com's Mark Feinsand last month, "I see [Donaldson] as a shorter-term, higher AAV type of option for a team in a win-now mode who has the depth to cover over potential injuries and under performance at the tail end of the deal." 
That mostly sounds right, though it doesn't have to be limited to win-now teams. In a lot of ways, Donaldson is the hitting version of Jake Arrieta, who entered last year's market as a recent superstar who had shown signs of beginning his decline. He signed for three years with the Phillies, who were hoping to prove they could begin their next competitive cycle, not urgently win a title in year one.

That means that we shouldn't rule out a team like the White Sox, who are apparently showing interest in both Harper and Machado, or the Phillies, who badly need to upgrade their lineup. The Cardinals are often cited as the front-runner, though their lineup is overwhelmingly right-handed already; teams in or near contention like the Braves, Mets, Angels, Rays and Twins might also show interest. A return to Cleveland isn't out of the question, either, since Yandy Díaz is currently penciled in as the Tribe's starting third baseman.
Basically, this is going to come down to health. You could see Donaldson playing 145 games, mashing at a high level. You could see the calf flaring up again and keeping him out of the lineup; you could see the shoulder preventing him from making the throw from third. Maybe that makes the fit better in the AL, since the DH would be available.
Donaldson's contract won't be what he expected it would have been two years ago. He's not the only free agent who can say that. Donaldson does, however, have the highest offensive ceiling of anyone available outside of Machado and Harper, and he's shown it recently. Someone will take the risk. They'll do that, because it'll be worth it.