Since Wolters made the transition from middle infielder to catcher, two things have been consistent for him: he's gotten rave reviews about his defense, and he hasn't hit. In two seasons with Akron, Wolters hit .233/.307/.300, but has also thrown just under half of potential base stealers (63/130). In addition, Wolters still has the ability to play the middle infield, and at times has started at shortstop or second base the day after he caught, which is quite an intriguing combination, especially with teams requiring bench players to play multiple positions. So that is why Colorado took a chance on Wolters; even if he never hits, his versatility can provide some value on a major-league roster. And if he does hit (even just a little), they may have themselves a starting catcher.
From Cleveland's standpoint, the loss of Wolters ended an experiment that did work, but at the same time didn't impact the major-league roster. Had Wolters stayed a middle infielder, he would have been fighting for playing time as a major-league backup with Jose Ramirez and Erik Gonzalez. Instead, he was blocked at the major-league level by Yan Gomez and Roberto Perez, both of whom have excellent defensive skill sets, and neither of whom are leaving any time soon.
Selected MLB Transactions
Webb was cut by the Dodgers last year and ended up pitching well for the Indians in a long relief role. The Rays almost certainly waited until the 18th to sign Webb because that way was the first day teams could placed players on the 60-day Disabled List. This roster maneuver will be a running theme this week for teams adding players to their 40-man rosters. Whitley was claimed off waivers from the Yankees this past November; he had Tommy John in May 2015.
(If you're wondering how the Indians will make room for Juan Uribe, I think they'll place Dylan Baker, who also had Tommy John surgery, on the 60-day DL)
The deal also includes numerous incentives for starts and innings pitched.
Minor was non-tendered by the Braves in December after missing the entire 2015 season after undergoing shoulder surgery. The Royals checked him out and apparently liked what they saw, or at least could live with a $7.25M gamble. Jason Vargas will miss most of the season after TJ surgery last August; he's one of many KC starters from the 2015 Opening Day roster who won't be active when 2016 begins.
Coleman was a big part of the Kansas City bullpen, but lost his spot in 2014 and wasn't a factor in 2015's championship run. McCarthy had Tommy John surgery last April, and could return at some point in the first half of the season.
The terms aren't exactly know yet, but the Dodgers will have Sierra through at least the 2021 season. Sierra, who is 24 years old, defected from Cuba last year, and because he's older than 21, the team who signed him would have to use their International free agent pool to do so. Sierra probably will spend some time in the high minors before reaching the majors; he's thought of as a potential 3/4 pitcher in a major-league rotation.
Montas was part of the three-team deal that sent Todd Frazier from the Reds to the White Sox. He could miss at least half of the season.