Liam Hendriks made his Major League debut in 2012 as a fringe starting pitcher for the Minnesota Twins, beginning a brutal stretch to kick off his career. In three years at Target Field, he posted a 6.06 ERA and struck out just 5.77 batters per nine innings.

Though he maintained a better-than-average walk rate in each of those seasons, his high-80s to low-90s fastball, paired with a sweeping slider, failed to keep opposing hitters off balance.

After Hendriks completed his age 24 season, Minnesota gave up on him. From December 2013 -- when he was waived by the Twins -- to October 2014, he changed teams five times. It was a period the former international signee from Australia called "tough" in an interview with FanGraphs last fall.

"Not knowing where I'd be kind of wore on me, and it wore on my wife as well," Hendriks said. "What we really wanted was stability, wherever that might be."

Last season, he found a temporary home in the Toronto Blue Jays bullpen and improved right away, posting a 2.92 ERA (2.14 FIP).

Though he struggled out of the gate this year following an offseason trade to the A's, he's regained his form in recent weeks to become one of the team's most intriguing bullpen pieces. Yes, he still has a 4.91 ERA. But after returning from the disabled list in June, he's allowed just three earned runs in 16.2 innings. And his peripherals (3.60 FIP, 3.89 xFIP) implicate a continued run of success.

But how did a faltering backend starter like Hendriks become a potential bullpen stud with excellent stuff? The answer is more interesting than you might have thought.

From Soft-Tosser to Flamethrower:

Bullpen Hendriks throws harder than starter Hendriks. Like a lot harder.

As a starter with the Twins, both his four seam and two seam fastballs had averaged 90 MPH. In 97.2 innings in relief over the past two years, he's upped that average to over 94 MPH on both pitches.

His other offerings are coming in faster, too. The sweeping slider now has more bite to it (more on this later) and has increased from 80.1 MPH to 87.9 MPH since his rookie season. Even his curve ball and change up, which he throws less often, are up a few ticks.

Transitions to the bullpen often correlate with increased pitch velocity, as pitchers go full-throttle without worrying about their stamina. Still, Hendriks' progress in this area has been more pronounced than usual -- his jump in velocity between 2014 and 2015 was larger than anyone in baseball by almost a full mile per hour, according to Baseball Prospectus writer Kyle Matte.

In an interview with reporter John Hickey before the season, the 27-year-old hurler attributed his pitch speed improvement to giving up alcohol, bulking up and changing his workout routine to focus on lower body strength. And with a sample size of almost 100 innings in relief, the change appears sustainable.

Put Some Spin On It:

Hendriks also added a rising effect to his four seam fastball to make the pitch more effective. Due to backspin on his heater, he's generating an average of 10.76 inches of perceived vertical movement per pitch, which is his career high and significantly better than the league average of 9.2 inches of vertical movement.

In turn, his four seam fastball has induced an excellent infield fly ball rate of 33.3 percent this year (and 29.5 percent for his career) due to its deceptive motion. Overall, hitters had a measly 37 wRC+ against the pitch last season and have a 91 wRC+ against it this season.

To complement his fast, deceptive heater thrown primarily in the middle to top-half of the zone, Hendriks throws a hard slider down in the zone. In fact, 88 percent of his sliders this season have darted low on hitters.

The pitch actually breaks less than it did when he threw it softer -- a typical tradeoff -- but the eye level change for hitters between his rising fastball and low slider creates a lethal pitch combination. Last year, hitters posted a 35 wRC+ mark when facing the slider. This year, that number has dropped to 26 wRC+.

In layman terms, that pitch is disgusting, y'all.

What You Were Doing, But Better:

The command Hendriks flashed as a starter has improved since he transitioned to the bullpen, making him a borderline elite walk preventer.

In all three seasons in Minnesota, he bested the league average for BB/9. But with the Blue Jays, he cracked the top 10 among all relievers with a 1.53 BB/9 mark. This season, he's No. 13 in the league in that regard.

Throwing harder has not had a negative impact on his control; instead, he's become more precise with his pitches and limited his self-destructive innings.

Still Waiting For the Luck to Turn:

In 286.1 career innings, Liam Hendriks has a .331 BABIP against him. This season that number sits at an incredible .362 mark. That's bizarre.

Pitchers are thought to have limited control of opposing BABIP, so a sustained number that far over the league average (this year the average is .297) is uncommon.

Hendriks did not have this problem in the minor leagues -- his two highest inning workloads in the minors (2012 and 2014) featured BABIP numbers under .280.

Contact type does not explain his BABIP struggles at the big league level either. This year, he has induced soft contact 24 percent of the time compared to the league average of 19 percent. And though his line drive rate is three percent higher than league average, it's not enough to explain the issue.

At some point, one would expect Hendriks' BABIP against to regress near the league average, which would go a long way in improving his overall numbers.

Conclusion:

Liam Hendriks is a different pitcher following his role change last season, and he now possesses the qualities teams look for in a high-leverage reliever. He throws hard, has a deceptive fastball-slider combination with unique characteristics and doesn't walk people. His peripherals suggest he's in line for a major breakthrough.

Also, he's 27 years old and under team control through 2019. For an A's organization desperate for affordable long-term pieces as it waits for the next crop of youngsters to break through the minor leagues, he's an excellent player to have around.

Hendriks might not ever make the jump to being a closer given his good-but-not-great strikeout rates in the bullpen, lack of consistent offerings beyond his four seam fastball and slider, and other in-house closing options like Ryan Dull. For him to take that step, his two seamer, which he throws 29 percent of the time but has almost no downward movement, would have to become a much better out pitch.

Still, he has the makeup to at least become Oakland's next great set up man. And he wouldn't be the first Australian flamethrower to have his best years coming out of the bullpen at the Coliseum.

*All data used in this article was taken from FanGraphs