Between now and Opening Day, teams will continue to look for ways to improve, plugging a hole here and supplementing their depth there. But this Hot Stove season already has seen plenty of transactions that should make a significant impact.
Which of these acquisitions represent the biggest upgrades? That is a complicated question, but projection systems, in this case Steamer, help provide an answer by forecasting the 2017 wins above replacement (WAR)* for every player .
• Hot Stove Tracker
Here are the 10 players acquired so far this offseason via free agency or trade whose 2017 projections provide the biggest increase in value over the players they are replacing.
10. Edwin Encarnacion, DH/1B, Indians
Projected 2017 WAR: 2.2
Replacing Mike Napoli: 1.0 in '16
Upgrade: +1.2
In Encarnacion, the defending American League-champion Indians are getting a player who is similar to Napoli, but a year younger and with a more impressive recent track record. If Encarnacion matches his 2016 production (.263/.357/.529, 134 weighted runs created-plus) he will bring a much more significant boost, but he is projected to slide a bit offensively in his age-34 season (123 wRC+).

9. Ian Desmond, 1B, Rockies
Projected 2017 WAR: 1.5
Replacing Mark Reynolds: 0.1 in '16
Upgrade: +1.4
Signing Desmond to a five-year, $70 million contract to man first base, a position he has never played, may have been an unorthodox move for Colorado. But the club did need help at the position after Reynolds surprisingly hit for average but not only moderate power last year, resulting in a slightly below league average 99 wRC+. Desmond bounced back with the bat after a rough '15, although it remains to be seen how he will handle his second position switch in as many seasons.
8. William Fowler, CF, Cardinals
Projected 2017 WAR: 2.1
Replacing Matthew Holliday: 0.7 in '16
Upgrade: +1.4
By snatching Fowler away from the division-rival Cubs, the Cardinals didn't replace Holliday directly, but the signing allows them to shift Randal Grichuk from center field to left. That should improve the club's overall outfield defense considerably, while Fowler brings his patient approach to the top of the lineup. The switch-hitter is projected to notch a .359 OBP, in line with his career mark of .366.

7. Taijuan Walker, SP, D-backs
Projected 2017 WAR: 2.2
Replacing Patrick Corbin: 0.5 in '16
Upgrade: +1.7
It's not clear at this point exactly how the Arizona starting rotation will shake out, but last year's group combined for only 8.0 WAR, ranking 21st in the Majors. Corbin wasn't the only D-backs starter to struggle, but he had a 5.58 ERA before shifting to the bullpen in August. In Seattle, Walker also endured a disappointing season, with a 4.22 ERA and 4.99 FIP in 25 starts. However, the former top prospect is only heading into his age-24 season, and projects to make strides in 2017.
6. Jaime Garcia, SP, Braves
Projected 2017 WAR: 2.3
Replacing Matt Wisler: 0.5 in '16
Upgrade: +1.8
Atlanta sought to bolster its rotation with veterans this offseason, not only acquiring Garcia in a trade with the Cardinals but also signing a pair of over-40 right-handers in Bartolo Colon (projected 2.2 WAR) and R.A. Dickey (1.8). Those three should provide some solid innings and buy time for the likes of Wisler and Aaron Blair to develop. Garcia is the riskiest bet of the Braves' new arms, having just completed his first season with more than 130 innings since 2011. But the lefty also is only 30, with a career ERA of 3.57.
5. Howie Kendrick, LF, Phillies
Projected 2017 WAR: 1.0
Replacing Cody Asche/Tyler Goeddel: -1.0 (average) in '16
Upgrade: +2.0
The Phillies wanted a solid veteran bat and got one in Kendrick, a longtime second baseman who saw the bulk of his playing time in left for the Dodgers last year. The 33-year-old will try to rebound from his lowest offensive output (91 wRC+) since he was a rookie in 2006. He should help Philly, which started nine different players in left -- Asche and Goeddel combined for 103 starts -- and got a collective 60 wRC+ and -3.6 WAR.

4. Josh Reddick, RF, Astros
Projected 2017 WAR: 2.6
Replacing Jake Marisnick: -0.1 in '16
Upgrade: +2.7
Houston also has added Brian McCann and Carlos Beltran to its lineup, but its biggest improvement came in signing Reddick to a four-year deal. While the left-handed batter figures to see most of his time in right, George Springer is expected to handle the move to center, displacing the slick-fielding Marisnick, who hit .209/.257/.331 in 2016. Reddick struggled after a trade to the Dodgers last summer but still has averaged 2.8 WAR per season since '12 and brings a formidable bat against right-handed pitching.
3. Jean Segura, SS, Mariners
Projected 2017 WAR: 2.2
Replacing Ketel Marte: -0.7 in '16
Upgrade: +2.9
Seattle paid a hefty price for Segura and two others when it sent Walker and the 23-year-old Marte to Arizona. On the other hand, Marte's 66 wRC+ was fifth-lowest among all players who received 450-plus plate appearances in 2016. Meanwhile, Segura experienced a profound resurgence in his age-26 campaign, hitting .319/.368/.499 with 20 homers, 33 steals and 5.0 WAR. He will have to acclimate back to short, however, after starting only 17 games there while spending most of his time at second.
2. Adam Eaton, CF, Nationals
Projected 2017 WAR: 2.5
Replacing Ben Revere: -1.2 in '16
Upgrade: +3.7
Washington did actually have one highly productive center fielder last year in Trea Turner, but he only finished third in starts at the position to Revere and Michael Taylor. With Turner now returning to his natural position of shortstop, Eaton takes over in center. The Nationals stunned many by giving up three highly regarded pitching prospects for Eaton, who is signed to a team-friendly extension that could run through 2021. As far as '17 goes, the Nats will hope Eaton can stick closer to his three-year average WAR (4.3) than his projection indicates as he returns to center.

1. Chris Sale, SP, Red Sox
Projected 2017 WAR: 4.7
Replacing Clay Buchholz: 0.5 in '16
Upgrade: +4.2
Boston made a splash at the Winter Meetings by landing Sale from the White Sox, and the left-hander ranks fifth among pitchers in the projections after generating at least 4.7 WAR in all five seasons as a big league starter. His arrival pushed out Buchholz, who was traded to the Phillies after a rollercoaster season in which he lost his rotation spot multiple times but finished strong, dropping his ERA to 4.78.
*The FanGraphs version of WAR was used in this piece.