The Padres have no obvious motivation to trade Logan Forsythe other than to acquire something they like in return. Forsythe was due to make the major league minimum, so he was as inexpensive as a Major League player can get. He is a somewhat versatile right handed bench bat that could have backed up both Chase Headley at 3B and Jedd Gyorko at 2B while playing corner OF or SS in a pinch. His hitting at the Major League level never developed into the asset it looked like it might based on his ability to get on base and hit with modest pop in the minors, but nevertheless was somewhat useful at the plate (for a backup infielder). All these reasons combine to make him someone the Padres could use in 2014, but also someone that could return something useful in trade.
The Rays decided that they liked the potential of Forsythe and were willing to give up something to get him. There are rumors that in total the deal will include at least 4 players (as reported by MLBDailyDish), however the one key something, well someone, mentioned coming over to the Padres is pitcher Alex Torres.Torres, according to SBNation's minorleagueball.com was the Rays' #3 prospect in 2012, before becoming just an honorable mention in 2013. He was profiled on the site as the Prospect of the Day twice. Once back in 2011, the season where he made his Major League debut. and then again last May just before his return to the bigs after a year spent in the minors.
If I were to summarize those reports and add a bit of research, I would say he is a small (5'10") lefty with deceptive stuff who gets a lot of strikeouts, but can be prone to wildness. That wildness kept him in AAA for a couple of seasons, but he finally seemed to break through in 2013. Most of his minor league career has consisted of being a starting pitcher, but all 43 of his Major League outings were in relief. The Padres have talked about wanting to add left handed relief pitching this offseason and this is a good addition in that regard. Plus, his experience as a starter would allow Bud Black to extend Torres beyond just situation pitching. A very versatile acquisition for the pen. In addition to that, Torres has less than a full season of big league service time and therefore is under team control through 2019.
Making this deal does decrease the Padres' infield depth. It also all but assures Alexi Amarista's spot on the major league roster in 2014. At 3B and SS, the Padres have two switch hitters that should play everyday when healthy. At second base, Jedd Gyorko looks to be an everyday sort of play as well. He bats right handed and makes for a more natural platoon with Amarista if needed. The team also can rely on Ryan Jackson to supply some glovework at SS and 3B. There is no guarantee he makes the team out of camp, but he is now nearly guaranteed to make some appearances with the club at some point in the season. If multiple injuries to any combination of SS, 2B and 3B were to crop up though, the team's 40 man roster would be quite stretched and someone would now have to be added. That is not a huge concern, but it is a new risk that the team is taking on with this deal. Or at least seems to be until we know more details about the other players involved.