Roy Halladay spent 12 years with the Blue Jays and won the 2003 AL Cy Young award in Toronto. (Andy Lyons/Getty Images)

Two-time Cy Young award winner Roy Halladay announced his retirement Monday morning after signing a one-day contract with the Toronto Blue Jays, the team that drafted him with the 17th overall pick in 1995 and for whom he pitched 12 of his 16 major league seasons. That announcement comes barely two years after Halladay, now 36, completed one of the most impressive four-year stretches of pitching in recent memory.

Alas, the 2012 and '13 seasons were plagued by shoulder problems that led to drops in velocity and effectiveness. Halladay had surgery this past May to repair a partially torn rotator cuff, frayed labrum and bone spur in his right shoulder, but he appeared no healthier after his return in late-August. He walked more men than he struck out over his last six starts while his fastball, which averaged 93 mph in his last Cy Young season of 2011, sat around 88 mph. Halladay's final major league appearance, in Miami on Sept. 23, lasted just three batters and 16 pitches, none of which topped 83 mph.

"It was tough," Halladay said at his press conference of the past two seasons. "To be able to go out there and know that it's probably not going to feel very good and I'm probably not going to be able to do things the way I want to is very frustrating."

Halladay will be best remembered for his four-season run as the best pitcher in baseball from 2008 to 2011. Over that stretch, he posted a 2.59 ERA, 160 ERA+, 1.07 WHIP, 6.14 strikeout-to-walk ratio and walked just 1.3 men per nine innings (all major league bests among pitchers who threw at least 650 innings over that span). He also led the majors during that stretch in wins (77), innings pitched (969 1/3), complete games (35) and shutouts (11, tied with Philadelphia rotation-mate Cliff Lee), averaging a 19-9 record, 213 strikeouts and 242 innings pitched per season.

For his career, he led his league in complete games seven times (and the majors four times), strikeout-to-walk ratio five times (four times topping all of MLB), shutouts and innings pitched four times, walks per nine innings three times, wins twice and WHIP and ERA+ once each. He made eight All-Star teams and finished in the top five in the Cy Young voting seven times, including six years in a row from 2006 to 2011, winning twice and finishing second two other times.

In 2010, his first year with the Phillies, to whom he was traded by Toronto the previous offseason because of his looming free agency, Halladay threw a perfect game in Miami. Later that year, in the first postseason appearance of his career, he threw just the second postseason no-hitter in major league history against the Reds in Game 1 of the Division Series. Counting that one, Halladay is the only man to throw two no-hitters in the same season since Nolan Ryan did it in 1973. Halladay never made it to a World Series, but he did post a 2.35 ERA in five postseason starts with Philadelphia. Clearly, he was a Hall-of-Fame-quality pitcher.

His talent was evident almost literally from the start of his career. He was considered an elite prospect and in just his second major league outing, back in September 1998, he came within one out of throwing a no-hitter, only to lose it when the Tigers' Bobby Higginson hit a home run to leftfield.

Despite that gem, Halladay's early career was a struggle. Mechanical issues led to him posting a 10.65 ERA in 13 starts and three relief appearances for Toronto in 2000 at age 23, after which he was sent down to High A to have his delivery rebuilt (and his head examined by a pair of sports psychologists). Thus, he didn't have his first great season until the age of 25, when he went 19-7 with a 2.93 ERA (157 ERA+) in a league-leading 239 1/3 innings for Toronto in 2002. He won the American League Cy Young award the following season, but shoulder problems limited him to 133 innings in 2004 and a comebacker broke his leg in early July of 2005, ending his season.

Healthy again in 2006 and '07, Halladay was again one of the league's better pitchers, but he reached another level in 2008. In an interview with SI.com's Tom Verducci earlier this year, Halladay credited some of that success to a tip Mariano Rivera gave him about how to hold his cutter during that year's All-Star Game at Yankee Stadium.

. . . the biggest thing was his finger placement and how his thumb was under the ball. I was throwing a cutter, but it was inconsistent. Once he told me about the thumb, it became a big pitch for me. You're so used to playing catch and four-seaming the baseball that your hand wants to go to that natural position. You have to keep reminding yourself, thumb underneath, thumb underneath. After that meeting I took a baseball and marked it with my finger and thumb placement for the cutter. If the pitch was ever off, I could go back to the baseball and hold it. I still have that ball. What he did for me was unbelievable. . . . After the All-Star Game that year, I pitched against the Yankees [three times] and beat them each time. I found out later that they fined Mariano in kangaroo court for me beating them with the cutter he taught me.

Halladay's splits that season suggest he was doing just as well on his own before that fateful lesson from Rivera (he did make the All-Star team, after all), but his cutter was undeniably his best pitch during that four-year run of dominance from 2008 to '11.

The question now becomes: Was Halladay a Hall of Famer despite his late start and the injuries which first interrupted and have now cut short his career? There's certainly a precedent for the election of a late-blooming pitcher who was the best in baseball over a multi-season span and whose career ended early due to injury.

Comparing Halladay to Sandy Koufax may seem like a stretch to some, but within the context of their era and ballparks, their Hall of Fame cases are quite similar. Remember, Halladay spent most of his career in the powerful American League East where, thanks to the unbalanced schedule, he regularly faced Yankees and Red Sox teams that boasted some of the most powerful lineups in one of the game's most offense-heavy eras. Koufax, meanwhile, pitched off a high mound and had the benefit of a larger strike zone and run-suppressing Dodger Stadium during the most pitching-friendly period of the live-ball era.

As a result, Koufax's park adjusted ERA+ (which is measured against league average) over his six All-Star seasons was 156. Halladay's ERA+ over his six best seasons (2002-03 and 2008-11) was 157. Over their careers, both posted a 131 ERA+, Koufax doing so in 2,324 1/3 innings, Halladay in 2,749 1/3. Halladay also won 203 games to Koufax's 165, doing so at a higher winning percentage (.659 vs. .655).

Turning to Jay Jaffe's JAWS system, Halladay had a Hall of Fame seven-year peak, posting a combined 50.6 WAR in his seven best seasons against the average Hall of Fame pitcher's 50.2 and Koufax's 46.1 (Koufax didn't have seven peak seasons; he only qualified for the ERA title seven times, doing so with a league-average mark in the first of those). Halladay falls short on the career measure, as would be expected, but not by a lot (57.6 WAR to the average Hall of Fame pitcher's 61.4, Koufax is at 47.5).

Still, Halladay certainly looks like a man with Hall of Fame credentials. Given how dominant he was, the amount of times he led his league and the majors in key categories, his eight All-Star appearances, his performance in the Cy Young voting, his historic no-hitters and the fact that he aces Bill James' Keltner List, Halladay should one day have a bronze plaque in Cooperstown.

Halladay's greatness only makes his early retirement all the more painful, but it's also to his credit that he recognized the end when it came.

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