The Angels are likely to replace either GM Jerry DiPoto or manager Mike Scioscia before the 2014 season, FOX Sports' Jon Morosi reports (in a series of tweets). Morosi explains that there are "philosophical differences" between DiPoto and Scioscia that make continuing on with both of them "not tenable."
Relations between DiPoto and Scioscia have been strained since at least early in the 2012 season, as Bill Shaikin of the Los Angeles Times noted in May of that year. The two disagreed over the firing of hitting coach Mickey Hatcher, and Ken Rosenthal of FOX Sports wrote in late 2012 that Scioscia also disliked assistant GM Scott Servais, and was "resistant" to using DiPoto's staff's statistical data.
Scioscia is signed to a ten-year contract that continues through 2018, with salaries of $6MM annually from 2016 through 2018. So if the Angels were to fire Scioscia, they would have to eat the remainder of that contract. DiPoto is only signed through 2014. Scioscia's contract is mostly a sunk cost, of course, and hiring a new manager wouldn't require the Angels to pay nearly as much. There's also the possibility that Scioscia could end up with another team. But as Morosi notes, Scioscia's contract could be a factor.
Another factor potentially in Scioscia's favor is that he is not directly responsible for many of the Angels' most troublesome decisions in the past two years, including the big-ticket signings of Albert Pujols and Josh Hamilton and the trade of Jean Segura and two other players for 13 starts by Zack Greinke. Scioscia also is not responsible for the Angels' farm system, which currently rates as one of the worst in baseball.