Liriano has elite stuff but problems harnessing it, leading to poor results.
As a fan of the two Bay Area baseball teams, most of my observed impressions of players around Major League Baseball are based on their performances against the San Francisco Giants and Oakland A's.
On July 13th of last season, I saw him throw his best game of the season against the A's. He went eight innings, struck out 15, walked one and allowed only four hits. Unfortunately, one of those hits was a grand slam off the bat of Jonny Gomes to give the A's a lead they wouldn't relinquish.
Despite the mistake to Gomes, Liriano's outing was one of the most dominant performances that I witnessed all season. His fastball was in the 92-95 mph range, and he featured a nasty slider and changeup—two swing and miss secondary pitches.
Yet that July night was the high-water mark in what was otherwise another maddening season for the talented lefty. Despite having excellent fastball velocity and a wipe-out slider, Liriano was demoted to the bullpen before returning to the rotation in time for a midseason trade. He finished the season with a 5.34 ERA in 156.2 innings.
He was 14th in the league in strikeout percentage amongst starters who threw at least 140 innings, proving that he still has some of the best stuff in the game. However, his control continued to hold him back as he finished with the third-highest walk ratio.
Liriano also had a hard time getting right-handed hitters out last season. He held lefties to a .221/.310/.293 batting line, but righties slashed .251/.354/.430 off him.
Part of the reason for his platoon split is that the slider is his best offering, and that pitch is much more effective against lefties. His changeup—which he uses to attack righties—was outstanding in the start I watched against the A's, but it was otherwise an inconsistent pitch for him last season.
Liriano also had issues pitching out of the stretch. Opponents had an OPS of .796 with men on base compared to just .699 with the bases empty.
Thus, while the Pirates are getting a pitcher with elite stuff, they're also getting a guy who has a hard time throwing strikes, getting righties outs and pitching from the stretch.
Last winter Pittsburgh took a similar gamble on the talented but enigmatic A.J. Burnett when they acquired him from the New York Yankees. Burnett rewarded the Pirates by trimming nearly two runs off his ERA, predominantly by reducing his walk and home run rates.
It isn't hard to imagine Liriano having the same success in his change from the American League to the National League with the Pirates. Just two seasons ago, he ranked as one of the best pitchers in the AL when he put up a 3.62 ERA and four Wins Above Replacement (WAR).
He's battled injuries and inconsistency since that excellent season, but he's young enough to get the magic back. As with Burnett, Liriano's stuff is still plenty good enough to miss bats.
The trick will be getting him to attack the strike zone the way he did two years ago and the way the Pirates got Burnett to last season. As with Burnett, this is a short-term bet on a player with excellent stuff and serious upside, but also with significant flaws.
This is a "boom or bust" deal for the Pirates, but the potential reward far exceeds the financial cost of the contract. When you haven't made the postseason in two decades, these are the types of gambles that you have to take.