Coming off arguably his best season yet, the Mets signed 39-year-old Justin Verlander to a two-year contract that, according to a source, is worth $86.7 million and includes a $35 million vesting option for 2025.

On the surface, it's not hard to justify those numbers. Verlander just went 18-4 with a 1.75 ERA over 27 starts for the World Series champion Astros in 2022, winning the AL Cy Young Award -- his third career honor -- in unanimous fashion and finishing 10th in AL MVP voting.

But what can the Mets expect from Verlander, who will play the entirety of his two-year deal after turning 40 years old in February? Though rare, it's not unprecedented for a big league pitcher to continue his dominance well into his 40s -- and even continue winning Cy Young Awards.

With that in mind, let's take a look at the five best single-season performances by pitchers during the Expansion Era (since 1961) after turning 40 years old. Though many of the following pitchers had multiple impressive seasons in their 40s, we picked only their best ones for the purposes of this list.

Roger Clemens, 2005 (Astros)
Age: 42

Clemens won the Cy Young Award one year earlier at the age of 41, but we’re instead highlighting his 2005 season. Sure, he was brilliant in ’04, going 18-4 with a 2.98 ERA and 218 strikeouts, but he was even better at the age of 42.

After all, Clemens posted a Major League-best 1.87 ERA over 32 starts while helping lead Houston to the AL pennant. He’s the oldest pitcher to ever post a sub-2.00 ERA -- and the only AL/NL pitcher with a lower ERA after even turning 40 is Cy Young, who put up a 1.26 ERA in 1908 at the age of 41. Clemens finished third in NL Cy Young voting in 2005, checking in behind a pair of 20-game winners in Chris Carpenter (21-5, 2.83 ERA) and Dontrelle Willis (22-10, 2.63).

Incredibly, Clemens had a 2.99 ERA in five seasons after turning 40 years old. He went 61-33 during those five years while averaging 27 starts per season and putting up a 146 ERA+.

Randy Johnson, 2004 (D-backs)
Age: 40

After winning four consecutive NL Cy Young Awards from 1999-2002, it had appeared as if age might finally be catching up with Johnson in an injury-plagued 2003 campaign. He struggled out of the gate while attempting to pitch through a right knee injury that ultimately required surgery and sidelined the Big Unit for nearly three months. Even upon his return, Johnson wasn't his usual self, finishing with a 4.26 ERA in 18 starts, all while celebrating his 40th birthday that September.

Any concerns were quickly put to rest the following season. Johnson tossed a two-hit shutout in his third start of the year, then topped it with a 13-strikeout perfect game on May 18. By the time all was said and done, he had racked up 290 strikeouts over 245 2/3 innings while recording a 2.60 ERA in 35 starts. No other 40-year-old pitcher has had more than 218 K's -- let alone 290 -- since the turn of the century.

Johnson narrowly missed out on his sixth Cy Young Award, finishing instead as the runner-up to … a 41-year-old Clemens.

Nolan Ryan, 1987 (Astros)
Age: 40

Ryan pitched seven seasons after turning 40 years old -- and we could have made an entire separate list out of his individual performances. When trying to narrow it down to his best post-40 season, you could pick 1989 when he racked up 301 strikeouts at the age of 42 (the only 300-K season by a pitcher in his 40s). You could go with ’90, when he threw his sixth career no-hitter at the age of 43. Or one year later, when he tossed his seventh and final no-hitter en route to holding opponents to a .172 average in ’91 at the age of 44.

But instead, we’ll zero in on Ryan’s 1987 campaign. Don't be fooled by his 8-16 record -- he was utterly dominant all season. Ryan had an NL-best 2.76 ERA and a Major League-leading 270 strikeouts. He also led the Majors in opponents' batting average (.200) and strikeout-to-walk ratio (3.1). And at a time when a pitcher's win-loss record was valued perhaps above all else, Ryan still managed to finish tied for fifth in NL Cy Young voting. With his same metrics, he likely would have won the honor in '87 if pitchers were evaluated then the way they are today.

Bartolo Colon, 2013 (Athletics)
Age: 40

Colon’s sudden resurgence at the age of 40 was made all the more impressive by the fact that it had appeared his career was winding down as early as 2006. After going 21-8 with a 3.48 ERA and winning the 2005 AL Cy Young Award with the Angels, Colon went just 1-5 with a 5.11 ERA while making only 10 starts in an injury-plagued ’06 campaign. He made only 37 starts over the next three seasons from 2007-09 -- and put up a 5.20 ERA in the process -- before missing the entire ’10 campaign after undergoing surgery to repair lingering shoulder issues.

Colon put up respectable numbers upon his return, going 18-19 with a 3.72 ERA over 53 outings from 2011-12, but he turned back the clock in '13. The right-hander went 18-6 with a 2.65 ERA over 30 starts, while leading the Majors with three shutouts. Colon finished sixth in AL Cy Young voting -- and made his first All-Star appearance since his Cy Young-winning ’05 season.

Phil Niekro, 1979
Age: 40

Like Ryan, Niekro pitched deep into his 40s -- and turned in some decent performances across multiple seasons. Relying on his legendary knuckleball, Niekro put up volume numbers in 1979 that will absolutely never be seen again, regardless of age. He led the NL in wins (21) … and losses (20). Niekro pitched a ridiculous 342 innings across 44 starts -- and he tossed a complete game in 23 of those 44 outings. All of those numbers led the Majors -- and no pitcher has made that many starts or logged as many innings in a season since.

Niekro was rewarded for his durability by finishing sixth in NL Cy Young voting and even garnering a share of MVP votes. He also won a Gold Glove Award. In fact, the Hall of Famer earned four of his five Gold Gloves and made two of his five All-Star appearances after turning 40 years old.

Honorable mention: Warren Spahn (1962), Dennis Martinez (1995), Tom Seaver (1985), Kenny Rogers (2005), Jamie Moyer (2003), John Smoltz (2007), David Wells (2003)