In February, Mike Napoli signed with the Rangers, returning to the club he played for from 2011-12 and again for part of '15. After spending most of the previous four seasons in the American League East and Central with the Red Sox and Indians, the reunion also brings Napoli back to the AL West.
Thanks to the unbalanced schedule, that means Napoli could play 19 games this season against his original team, the Angels. The first comes on Tuesday night in Anaheim, where Texas opens a three-game series.
This is notable because no current player has tormented a former team as much as Napoli has the Halos. The organization selected him in the 17th round of the 2000 Draft, first brought him to the Majors in '06, then traded him to the Blue Jays in the ill-fated Vernon Wells deal before the '11 season (Toronto almost immediately flipped him to Texas). Napoli has done his best to make Angels fans bitter about that transaction ever since.
Yet the slugger isn't alone when it comes to making a former employer pay. Here is somewhat subjective ranking of 10 active hitters who have done the most damage to an ex-team, looking only at their numbers since leaving, with a minimum of 75 plate appearances:

1. Napoli vs. Angels
Stats: 254 PA, .343/.449/.690 (1.139 OPS), 19 HR, 44 RBIs
Napoli's 73 hits against the Angels have come over six seasons, in three uniforms, in four stadiums and off 27 different pitchers, only a few of whom are currently on the club's active roster. In other words, Napoli's dominance over the Halos has been notable but isn't necessarily predictive in 2017 -- and the same could be said for the others on this list. Still, Napoli has hit the Angels harder than any other AL team. That includes a lights-out '12 campaign in Texas (.442/.567/.904, 6 HR, 16 RBIs) and another last year in Cleveland (14-for-28, HR, 7 RBIs). 
2. Daniel Murphy vs. Mets
Stats: 81 PA, .413/.444/.773 (1.218 OPS), 7 HR, 21 RBIs
It's only one season so far -- the Nationals head to Citi Field on April 21 -- but what a season it was. The Mets didn't re-sign Murphy following his postseason breakout, and now he has more career homers against New York than he does against his current club (six in 404 plate appearances). Murphy got a hit in all 19 matchups last year, while the Nats went 12-7 and won the division by eight games.

3. Matthew Holliday vs. Rockies
Stats: 170 PA, .378/.453/.696 (1.149 OPS), 11 HR, 37 RBIs
After the 2008 season, Colorado traded Holliday to the A's for three players, including Carlos Gonzalez and Huston Street. Since then, Holliday has returned to Coors Field for 18 games -- all with the Cardinals -- and he has gone 28-for-64 (.438) with seven homers, seven doubles and nine walks. However, he is only 2-for-13 against the Rox since '15 and isn't scheduled to face them this year with the Yankees.
4. Nelson Cruz vs. Rangers
Stats: 175 PA, .299/.360/.580 (.940 OPS), 12 HR, 28 RBIs
After leaving Texas as a free agent, Cruz did only moderate damage to his former club in 2014 and '16, despite a total of six homers. But for AL West foe Seattle in '15, he went a blistering 25-for-61 (.410) with three doubles, a triple, six homers and eight walks in 16 matchups. Cruz's next shot at Rangers pitching, his first this year, will come on Friday at Safeco Field.
5. Victor Martinez vs. Indians
Stats: 417 PA, .314/.384/.510 (.894 OPS), 14 HR, 68 RBIs
Cleveland shipped Martinez to Boston at the 2009 non-waiver Trade Deadline, but he returned to the AL Central by signing with Detroit prior to the '11 season. Over the next four seasons -- though he missed all of '12 -- Martinez hit .358/.432/.617 in 53 games against the Tribe. He hasn't tasted nearly the same success since, with the Tigers set to visit Cleveland for a three-game series beginning on Friday.

6. Justin Upton vs. D-backs
Stats: 132 PA, .306/.409/.586 (.995 OPS), 8 HR, 21 RBIs
Upton was coming off a down year when the D-backs traded the 25-year-old to the Braves as part of a seven-player blockbuster in January 2013. The following season he went 9-for-22 (.409) against them, and in '15 slugged five homers and five doubles over 18 matchups with San Diego. After signing with the Tigers last year, Upton did not get to face his original club, but those two teams will meet four times in 2017 Interleague Play (May 9-10; June 13-14).
7. Carlos Beltran vs. Royals
Stats: 121 PA, .336/.393/.591 (.993 OPS), 6 HR, 19 RBIs
Beltran started twice against the Royals at Minute Maid Park this past weekend and went 2-for-4 with a double in both games. That's just more of the same from the switch-hitter, who was traded by Kansas City in 2004, but he didn't get the chance to face the club until '12. Since then, they have matched up each year, with Beltran posting an OPS above .900 all but once.
8. Melky Cabrera vs. Yankees
Stats: 186 PA, .304/.351/.544 (.895 OPS), 9 HR, 27 RBIs
Traded to Atlanta after the 2009 season, Cabrera got his first chance at the Yankees with the Royals in '11. Since that season, he has hit more homers against the Bronx Bombers than any other team, despite spending only two of those years in the AL East, with Toronto. Cabrera, whose White Sox visit Yankee Stadium from April 17-19, has reached base safely in 40 of 43 matchups.
9. Ian Kinsler vs. Rangers
Stats: 89 PA, .349/.393/.627 (1.020 OPS), 4 HR, 12 RBIs
There's been some acrimony between the two parties since Texas traded Kinsler to Detroit after the 2013 season, and Kinsler's bat certainly did a lot of talking that next year. In '14, he went 14-for-29 (.483) with five doubles, a homer and four walks in seven games against his ex-teammates. Kinsler has hit safely in 18 of 19 matchups, heading into his first opportunity of '17 (May 19 at Comerica Park). 

10. Carlos Gomez vs. Twins
Stats: 141 PA, .338/.363/.585 (.948 OPS), 6 HR, 21 RBIs
Those numbers don't count the three games Gomez played against the Twins when he debuted with the 2007 Mets, who the following February traded him to Minnesota as part of a package for Johan Santana. After two seasons, the Twins sent Gomez to the Brewers for J.J. Hardy, and eventually, Gomez blossomed into a star. From 2011-13 in particular, he hurt Minnesota in Interleague Play, going 14-for-34 (.412) with four homers while starting just seven games. Gomez has yet to return to the AL Central, but his Rangers are set to face the Twins seven times this year, beginning April 24-26 in Texas.
Honorable mentions:Yonder Alonso vs. Reds, Gregor Blanco vs. Braves, Jose Bautista vs. Rays, Shin-Soo Choo vs. Mariners, Adrian Gonzalez vs. Padres, Yasmani Grandal vs. Padres, Kelly Johnson vs. Blue Jays, DJ LeMahieu vs. Cubs, Brandon Phillips vs. Indians, Jayson Werth vs. Dodgers.