Rosales is something of a veteran, having made his major-league debut back in 2008, with the Cincinnati Reds. This is his second stint in Oakland, having also played for Texas in San Diego. Over his 10 seasons and 606 games in the majors, he has a line of .228/.295/.364, which works out at an OPS+ of 79. This year, over 223 plate appearances for the Athletics, Rosales is hitting .234/.273/.346 (OPS+ 69). He has played every position bar center and catcher - he even pitched a pair of innings in 2015! - but has about an even amount of innings as second, third and short, though the defensive metrics agree that 2B is his best position.
Fun fact: he’s a bit of a speedster around the bases. Not necessarily stealing them, but when he hits a home-run, he doesn’t so much have a trot as a gallop. Earlier this year, he lapped the bags in less than 16 seconds, according to Statcast breaking his own record for the fastest over-the-fences home-run circuit.
The prospect going the other was, Jeferson Mejia was acquired from the Cubs in the trade for Miguel Montero (along with Zack Godley). The pitcher, who turns 23 on Wednesday, has been with our Low-A and A-ball affiliates in Hillsboro and Kane County this season. He has a 6.21 ERA over 21 relief appearances between the two teams, with a K:BB of 35:25 in 29 innings, which suggests wildly uncontrolled raw stuff.