At the start of the 2015 season, the Boston Red Sox signed starting pitcher Rick Porcello to a four-year contract extension that would pay him $82.5 million through the 2019 campaign. Porcello would earn $20 million in 2016 and 2017, and $21 million a season in 2018 and 2019.

When the deal was first signed, it seemed like an overpay. At the time he was still just 25 years old and had put up decent numbers throughout his career, going 76-63 with a 4.30 ERA and 1.35 WHIP. But he only had an ERA+ of 97 (league average is 100) and had allowed 10.0 hits per nine innings while striking out only 5.9 per nine innings. Those concerns were confirmed when he went 9-15 in 28 starts last season with a 4.92 ERA, 1.36 WHIP and an ERA+ of 87.

Porcello was by no means bad, but he was being paid like a No. 2 starter and was producing back-of-the-rotation results.

This year is a different story.

On Top of His Game

After a complete-game victory over the Baltimore Orioles on Monday night, Porcello leads all of baseball in wins (21-4) and WHIP (0.98). He has 3.08 ERA and 3.44 FIP. In last night's complete-game win, Porcello struck out seven and walked none while allowing just two earned runs on four hits.

The most amazing is that Porcello needed just 89 pitches to twirl his nine inning opus.

Porcello is just the third Red Sox pitcher in the last 30 years to toss a complete game in under 90 pitches, joining Aaron Cook in 2012 and Roger Clemens in 1988. He now has 11 straight starts in which he's gone more than seven innings, which is tied with Clayton Kershaw for the most this season. No one in the American League has gone more than six straight starts with more than seven innings pitched.

And over his last 104 frames, Porcello is 11-2 with a 2.32 ERA.

Any way you slice it, Rick Porcello is on fire right now.

Parsing the Numbers

While his strikeouts per nine innings have dropped a bit over last year (7.80 to 7.43), his walks per nine have also fallen (1.99 to 1.24) and his home-run rate has really taken a turn for the better, dropping to 0.94 jacks per nine. And whereas last season opponents batted .284 against him, they're batting a meager .223 this season.

One big difference for Porcello has been his fastball. While he's not throwing any harder than last season (just 91.5 miles per hour this year), it has become a far more effective pitch. According to Fangraphs, his fastball's pitch value (wFB) is 13.8, meaning he has saved his team 13.8 runs over a league average pitcher on that pitch this season. Last year it was 0.6, and before this year, the most runs he'd saved on his fastball came in his rookie year back in 2009 when it was 15.7.

His off-speed pitches have improved, as well. Last year, his slider pitch value (wSL) was -4.1, and the year before that it was -5.7. This year, it's 7.3. And last season, his changeup pitch value (wCH) was -6.7, whereas this year, it's 11.1. That's a dramatic improvement.

He's basically throwing all of his pitches as well as he ever has.

Cy Young Discussion

So where does Porcello rank among American League Cy Young contenders?

He currently leads all American League pitchers in wins (21), strikeouts-per-walk rate (6.00) and WHIP (0.98). He is 2nd in walks per nine (1.24), his 3.08 ERA is 3rd, his innings pitched (201 2/3 IP) is tied for 2nd, and his 3.44 FIP and batting average against (.223) are 5th.

As for those all-important wins above replacement totals, his fWAR of 4.7 and his Baseball Reference WAR (rWAR) of 5.0 are both 5th. According to Fangraphs, the pitchers with a better WAR than Porcello are Chris Sale (5.2), Masahiro Tanaka (5.1), Corey Kluber (4.9) and David Price (4.8), and according to Baseball Reference, the pitchers above Porcello are Kluber (6.4), Tanaka (5.6), Justin Verlander (5.5) and Sale (5.4).

Porcello may not have the gaudy strikeout numbers and may not throw as hard as everybody else, but in an era when pitchers are blowing past 100 pitches by the sixth inning, Porcello is a throwback to when pitch economy was more highly valued. He routinely saves Boston's bullpen and, along the way, is getting just about everybody out.

He may not be the frontrunner for American League Cy Young, but he's certainly a top-shelf candidate. And along with Price, Porcello is giving the Sox a top of the rotation that no one wants to face in the American League playoffs.