But part of what makes the roulette wheel of an NFL season spin is the random snapping of ligaments and bones. One sticky square of turf, one awkward landing, one ill-fated pileup, and it’s back to square one.

Sometimes, injuries don’t have the effect you think they might. Last year, Seattle survived the losses of both Shaun Alexander and Matt Hasselbeck for month stretches and made the playoffs.

And certainly the season-killing injury to Donovan McNabb didn’t do any such thing to the Eagles, thanks to the clone-line play of Jeff Garcia (McNabb 95.5 rating, Garcia 95.8).

But some bad breaks were truly transcendent.

June 12, 2006: Steelers QB Ben Roethlisberger (broken jaw and nose).

A look back at the Steelers’ failed Super Bowl points to one major problem – the de-evolution of Roethlisberger. Coming a few inches from death in a motorcycle crash will do that to you.

The Steelers had similar numbers on defense in 2005 and 06, and had a better running game (4.25 average to 4.05). But shell-shocked Roethlisberger’s rating dipped from 98.6 to 75.4, and the Steelers couldn’t overcome it.

September 17, 2006: Eagles DE Jevon Kearse (torn ligaments, left knee).

An injury to “The Freak” was no huge surprise (he’d missed 23 games over the prior 4 seasons), but the Eagles’ defensive line hasn’t been the same without him. Opposite DE Trent Cole had four sacks in the two games Kearse played, but managed only four more since. As a team, Philly had 13 sacks in those first two games, only 27 since. They certainly could have used him against Drew Brees and the Saints in their divisional loss.

 
October 2, 2006: Ravens G Edwin Mutilalo (torn tricep).

The Ravens’ top run blocker went down after the Ravens’ win over San Diego, and running the ball remained Baltimore’s Achilles heel. Jamal Lewis managed just two 100-yard games, and Baltimore’s yards-per-carry average dipped from a subpar 3.55 in 2005 (27th) to an even-more anemic 3.44 (31st) in 2006.

October 9: Jaguars LB Mike Peterson (torn pectoral).

The Jaguars’ defense played pretty good football without their middle linebacker (18.2 points allowed without him, 14.8 with him), but he was missed most down the stretch – all of the Jags’ final five losses were by a touchdown or less, and you have to think Peterson (132 tackles, six sacks in 2005) might have been able to make a difference.

November 12: Giants LT Luke Petitgout (leg).

November was not a good month for Eli Manning. A week after losing his best underneath receiver (Amani Toomer), Manning lost his left tackle Petitgout in the first quarter of a loss to the Bears. Manning spent the rest of the season reverting back to his rookie struggles, with passer ratings under 70 in five of his seven Petitgout-less games.

December 3: Bears DT Tommie Harris, (hamstring).

The Bears made in the Super Bowl, so how did the loss of Harris change the season? Well, from all indications, the game would have been significantly closer had Harris not gotten hurt.

The Bears’ defense was top-notch with Harris, allowing 12.5 points - but when Harris went out, they allowed 26.3 a game the final four, and the struggles continued through the playoffs. Harris isn’t really worth 13.8 points a game (the per-game difference without Harris) to the Bears, but he’s worth a couple, and the Bears will probably always wonder if Harris was the difference in their Super Bowl loss.

December 3: Saints WR Joe Horn (groin).

The Saints’ success came mostly with the veteran Horn in the lineup – his nine-game production projected to a very Horn-like 1,175 yards and seven TDs over a full year.

The Saints were 4-4 without Horn in the lineup (6-3 with him), and his absence as a receiver and leader was pretty glaring in the NFC title game as guys like Terrance Copper and Devery “Dropsies” Henderson tried to fill his shoes. The sure-handed Horn has only three lost fumbles over seven seasons with the Saints. Of course, they liked life without him enough to cut him loose (a fate that also befell the previously mentioned Petitgout and Mulitalo).

December 31: Patriots S Rodney Harrison (ankle).

Patriots’ cornerbacks Ellis Hobbs and Asante Samuel  played lights out through the AFC playoffs – in three games, opposing WRs had a total of 25 catches among 120 throws attempted, and the duo knocked down an amazing 16 passes. (Meanwhile, the unheralded Pats wideouts had 46 catches over the same span.)

But the absence of Harrison was deadly to New England -– especially in the AFC title game, where Colt tight ends combined for 174 yards and the Pats allowed 93 yards rushing in the second half. Harrison, the emotional leader (and surest tackler) in the secondary, could quite possibly have been the difference between winning and losing in Indy.