After hearing that the other Steve Smith was retiring, Kyle on twitter asked me where Smith’s 2009 season ranked in the pantheon of anomalous wide receiver seasons. In case you forgot, take a look at Smith’s yearly production:

Smith had what looked like a breakout season in 2009, catching 107 passes for 1,220 yards and seven touchdowns. As it turned out, those numbers represent 44% of his career receptions, 46% of his career receiving yards, and 58% of his career touchdowns.

So how do we measure the biggest outlier seasons of all time? One way would be to compare each receiver’s best season to his second best season and see the difference. I used Adjusted Catch Yards — calculated as Receiving Yards plus five yards for every Reception and twenty yards for every Receiving Touchdown — to do that for every retired receiver and tight end in NFL history. The table below shows all receivers who gained at least 800 more Adjusted Catch Yards in their best season than in their second best season. For example, here’s how to read the Germane Crowell line. Crowell’s best season came with Detroit in 1999, when he caught 81 passes for 1,338 yards and 7 touchdowns. That’s equal to 1,883 Adjusted Catch Yards. In his second best year, he caught only 34 passes for 430 yards and three touchdowns, giving him only 660 ACY. That’s 1,223 Adjusted Catch Yards fewer than in his best season. Using this method, Steve Smith comes in with the sixth most anomalous season in NFL history.

• Number one on the list might look familiar to you: that’s former Vikings head coach Bud Grant, who played only two years in the NFL before moving to the CFL (where he also began his coaching career). Grant was a defensive end in his first season and recorded no catches, but in his only season as a receiver he finished second in the league in both receptions and receiving yards.
• Patrick Jeffers, Muhsin Muhammad, and Steve Beuerlein took the league by storm in the second half of the ’99 season. For Jeffers and Beuerlein, they were never able to reach those levels again, while Muhammad did have one more dominant season in 2004.
• Michael Clayton and Sylvestor Morris both had impressive rookie seasons. In Morris’ third NFL game, he went for over 100 yards and three touchdowns against the Chargers. Unfortunately, a series of injuries that began in mini-camp in 2001 ruined his career. Clayton’s injuries weren’t as debilitating, but he also suffered a series of injuries after his rookie season. At least Clayton rebuilt himself into one of the better blocking receivers in the league and a solid possession receiver, but he never again flashed the potential from his rookie year.
• Pat Studstill makes the list, but I already chronicled his interesting career.

Here’s one other way to look at outlier seasons. I looked at all receivers, including active players, who played for at least four years. I then calculated their number of Adjusted Catch Yards in their best year and their career average Adjusted Catch Yards per season (including the best season). The next table takes a look at the 50 receivers with the highest peak season relative to career average. Receivers who stuck around for a really long time (Jerry Rice, Isaac Bruce) lowered their career averages enough to make their top seasons really stick out; still, I think this method does a good job of identifying some players the prior method might have missed.

Here’s how to read the table below. Robert Brooks, playing for the Packers in 1995, caught 102 passes, gained 1,497 receiving yards, and scored 13 touchdowns. Brooks gained 2,267 ACY that season, and played eight seasons in the league. In his eight seasons, he averaged 808 ACY, meaning he gained 1,459 more ACY in 1995 than he did in his average season.

Boston squeezes the life out of an innocent pen.

• Another Brett Favre wide receiver shows up high on the list. Javon Walker had a monster season in his third year, but then became a cautionary tale for players everywhere. After a very public and bitter holdout, Walker returned to the Packers in time for his fourth season… and tore his ACL in the first game of the ’05 season. He went to the Broncos and had a 1,000-yard season in 2006 that ended in tragedy. Walker was with Darrent Williams at a New Year’s Eve party; Williams was shot in their limousine and died in Walker’s lap. Walker later went to Oakland, and three months later, he was robbed in Las Vegas and knocked unconscious. He gained just 196 yards in two seasons with the Raiders.
• Three years before Walker’s breakout, David Boston looked to be the next superstar wide receiver when he led the league in receiving yards in his third season. But Boston missed half of the 2002 season due to a torn right patella tendon, and signed with the Chargers after the season. Boston’s time in San Diego was marred with attitude problems, injuries, and steroids accusations. He was the size of a tight end by the time he joined the Dolphins in 2005, when he gained 80 yards in one season with Miami.
• Koren Robinson was a top-ten pick and then gained 1,240 receiving yards at age 22 in 2002. But substance-abuse problems derailed his career, turning him into a massive waste of potential. Sidney Rice had a 1300-yard season in his third year — he’s another Brett Favre breakout — but injuries have prevented him from reaching those heights again. Braylon Edwards caught 16 touchdowns during Derek Anderson‘s fluky 2007 season, but Edwards has been more potential than production every other season of his career.