It's the second time Liriano,30, has won the award, taking home the honor in 2010 with the Minnesota Twins.
The Pittsburgh Pirates were quick to offer their congratulations to their pitcher.
Rivera's selection, meanwhile, was a no-brainer. The 43-year-old injured his knee last year and ended up missing the rest of the 2012 season after making just nine appearances through April. Some probably even wondered if Rivera would ever don the pinstripes again. At his age, how could he possibly return and be anything close to his best?
The answer is that Mariano Rivera is superhuman. In his final season in the league, the Yankees closer had 44 saves (third in the AL) to go along with a 2.11 ERA.
Now the problem will be where to put this award. He's already received the All-Star Game MVP and Commissioner's Historic Achievement Award this year, not to mention the many gifts he received at visiting ballparks during his season-long farewell tour.
Perhaps most importantly, at least Rivera will now have a more pleasant reason to remember the Nov. 4 date.
Not to be outdone, Liriano had a career revival of his own in Pittsburgh.
Most fans and baseball experts had written off the left-hander before he moved to the Pirates. He had finished 6-12 in 28 starts for the Chicago White Sox and Minnesota Twins in 2012, compiling a robust 5.34 ERA.
Then he went and compiled a 16-8 record and 3.02 ERA in 2013, playing a huge part in making the Pirates' first postseason appearance since 1992 possible.