The details aside, this move is a head scratcher because it means that the team is inclined to keep Sergio Mitre for the start of the season, and is willing to part ways with Gaudin.
For the record, Chad has a career ERA+ of 94, which is just below average, while Mitre has a career ERA+ of 78. My math skills aren't what they used to be, but I'm fairly confident that 94 is better than 78. The impetus for cutting Gaudin now appears to be his poor spring. Mitre has had a stronger spring, but baseball is full of examples of players who had strong springs and awful seasons. As far as I'm aware neither pitcher has provided evidence to suggest a diversion from career averages this season.