Fantasy Football "Breakout Player" Definition
A "breakout player" is a fantasy football player who has been ineffective or marginal in the past, but who suddenly becomes a fantasy football stud one year. Breakout players happen every year in fantasy football, and the teams who acquire those breakout players often challenge for their league title. That's because a breakout player outperforms wherever they were drafted in the fantasy football draft, meaning that owner gets better value than other owners and a major advantage in their starting lineup every week. Fantasy football owners draft "sleeper candidates" every year, hoping to add that breakout player.
Breakout fantasy football players can happen in any year of their NFL career and at any point in the fantasy football draft, though most players who haven't broken out won't be drafted in the highest rounds of a fantasy draft. Occasionally, you'll get a highly valued player or a talented but often-injured player who gets drafted high anyway, though. But whenever a fantasy player hasn't been a factor in fantasy football before, and suddenly becomes a fantasy football factor, that player is considered to be having a breakout year.
Breakout Year - Third Year Wide Receivers
It's a theory in fantasy football that wide receivers often "break out" in their third NFL season. Most NFL rookie receivers are inconsistent or totally ineffective, because they haven't learned the route-running skills and defense-reading skills that NFL receivers need to be breakout players. There are only a handful of wide receivers (Randy Moss, Anquan Boldin) in NFL history to have had 1,000 receiving seasons. That means it's usually a bad bet to draft a rookie wide receiver in fantasy football.
Many NFL receivers show marked improvement in their 2nd NFL season and are trusted a little more by their quarterback to be in the spot the play calls for them to be in. Indeed, there are some breakout wide receivers in their second season. But it seems that enough NFL wide receivers haven't truly learned the skills needed to consistently beat an NFL cornerback and find the soft spot in NFL defenses until their third year, so many fantasy football owners like to draft NFL receivers when they are coming into their 3rd NFL season - in hopes of drafting a breakout wide receiver.
Breakout Year - Fantasy Football Players
Breakout years can happen in just about any year of an NFL career, though. NFL running backs can often have highly productive rookie seasons, because running with the football is more of an athletic process than the cerebral process that the NFL passing game can be. If a running back is fast, elusive and can break tackles, that running back is likely to be trusted by his NFL team to run the ball a lot. At the same time, some NFL coaches don't trust a rookie runner to pick up blocking assignments on pass plays, so they limit their rookie RBs plays to avoid getting their quarterback killed on a missed blocking assignment. For this reason, I've found that NFL running backs often break out in their 2nd NFL season - because they are trusted to "play every down".
NFL quarterbacks and tight ends often follow the same pattern as a wide receivers, for the same reasons. NFL defenses and defensive coordinators spend a lot of their time disguising their coverages and blitz packages, to fool quarterbacks and their receivers into either throwing to the wrong spot, or holding the ball too long (thus causing sacks or turnovers). So it becomes a process for any NFL players involved heavily in the passing game to learn how to read coverages and defensive alignments. For this reason, it often takes a year or two for NFL quarterbacks to have their breakout year. There are exceptions, though even the surprisingly good rookie quarterback (Matt Ryan, Joe Flacco, Peyton Manning further back) while often have trouble with some aspect of the NFL game (Ryan and Flacco still were bus drivers mainly, while Peyton Manning threw 29 interceptions his rookie year).
When drafting a sleeper pick and hoping for a breakout year, try to see which players have break out opportunities. Look for players getting their first real chance to start in the NFL, often through free agent defections or retirements. For instance, Anthony Gonzales (now injured) was looked at as a good breakout candidate, because Marvin Harrison was waived by the Indianapolis Colts, and subsequently retired. Ray Rice was considered a breakout candidate, because he had replaced Willis McGahee as the Baltimore Ravens starting running back.
Often, breakout players come from unexpected places. Look at Mario Manningham, an early breakout player two weeks into the NFL 2009 season. Manningham is a 2nd year receiver and the Giants are looking to replace Plaxico Burress and Amani Toomer. Interestingly, the New York Giants had Steve Smith and Domenic Hixon slated to be the starting WRs, while they drafted Hakeem Nicks and Ramses Barden as their potential wide receiving starters of the future. Mario Manningham was lost in the mix as the 3rd receiver, but a player who would likely have playing time cut when Hakeem Nicks became a viable NFL receiver.
So when Hakeem Nicks and Domenic Hixon both received injuries in the Giants Week 1 game, Mario Manningham was suddenly thrust into a much greater role. Manningham had a touchdown in Week 1 and 150+ yards and a touchdown in Week 2, and suddenly a player lost in the shuffle appears to be a possible 2009 breakout player.
Fantasy football works in strange ways.