Time of possession is often cited as "the most overrated statistic in football" or some such, and as an aspect universally regarded as "overrated," probably falls into the category of "rated more or less properly," in general. Which does not stop Brian from indicting good old TOP with something like venom this morning on his venerable MgoBlog:
The possession is the atom of football, as well, and they can vary even more wildly than they can in a basketball game. Michigan and Minnesota had eight meaningful possessions in their recent game; last year against Northwestern they had more than double that number. And yet the yardage totals ceded were added up in a raw state and presented plainly even though Michigan's defense had twice the opportunities to fail and bend and cede points. And no one ever notices this. In football, the play's the thing, but it's just an electron or a proton or whatever. The possession is the atom.
Semantically, SMQ would argue the possession is the molecule, and plays are the atoms (electrons and protons would be the formations, players the quarks, or however those invisible entities are alleged to be divided), but in general the "possession as basic unit of measurement" approach is a sensible one bordering on intriguing and probably deserving of some further wonky huffing.
Basketball is one thing, but football may not be ready for this
But to the main point, Brian is right that it's also obviously correct - a tautology, to steal the term - that TOP is an effect, not a cause, and that the quality of the time is vastly more important than the quantity. In most games, which are not decided in the final few minutes or by a single drive, "time of possession" and even "number of plays run" have little impact on the outcome.
Possession can be a telling effect, though, and SMQ would say Brian is off when he says, "You cannot `keep the ball away from your opponent,'" or, to end a paragraph otherwise defending the stat's current usefulness in a passer friendly world, "the amount of time you have the ball doesn't matter." If you're an underdog, or don't have a lot of confidence in your defense, it should matter, because the doctrine of "shortening the game" by running, eking out first downs and holding on to the ball as long as possible hasn't persisted for nothing. Especially on a "per possession" basis, some teams have a tangible interest in limiting the number of possessions by the opponent, which requires a gameplan that, if successful, almost has to result in a time of possession advantage. Again, an effect, not a cause, but a telling effect.
Recent example: Auburn at South Carolina. Much was made of time of possession in this game, because of the extreme anomaly of USC not getting hold of the ball for an entire quarter. Less advertised was that South Carolina actually "won" time of possession for the game as a whole in spite of Auburn's two third quarter marathon drives, and probably could have never been in a position to win the game at the end without turnovers - which it did not get - otherwise. Before AU got too conservative up a touchdown in the fourth quarter, South Carolina had managed to stop the Tigers once in five possessions. USC itself had moved the ball surprisingly well, well enough to keep up - one of the reasons Steve Spurrier was credited with such a great gameplan and playcalling - but it's not nearly as difficult to keep up when your opponent only has five real possessions and goes conservative with the lead on the sixth, giving you a chance to drive for a win. "Per possession," to that point, South Carolina had managed to more or less match up - but given all we and Spurrier knew then about the respective talent levels and previous performances of Auburn and South Carolina, would this have been true over eight possessions? Ten? Over the course of more possessions, it's not a wild guess to imagine that South Carolina's offensive success would have petered out well before Auburn's; the Gamecocks undoubtedly benefited from limiting the number of times its defense had to try to stop Brandon Cox and Kenny Irons, and presumably moreso than Auburn did by limiting the number of times it had to stop Syvelle Newton, however hot he was on this particular night. The raw number - 30:20 to 29:40 - says nothing without context, but possession time was an essential strategic aspect of the game.
Possession time can matter within segments of a game, too: Auburn won that night because it hijacked USC's plan via the ballyhooed onside kick and spent 30 plays to run off the entire third quarter on two scoring drives that were the difference on the scoreboard. Two days later, Ohio State scored 17 points from 7:36 in the third quarter to 14:59 in the fourth, on three possessions that collectively spanned about 18 ½ minutes. Iowa, meanwhile, in the same span, had two possessions covering a little over three minutes together, did not score. So a 14-10 game was 31-10, just like that. Iowa, which had been running the ball successfully for the first quarter and a half, needed to play the clock control game in order to continue to run the ball and reduce the explosive Buckeyes' chances to strike on the Hawkeye defense; OSU did this instead, running and eating up time to protect its own young defense, and Iowa, in turn, had to abandon the successful aspect of its attack to play wild, unsuccessful catch up ball in the fourth quarter. Its final three drives of the game covered five total plays, three of which were turnovers, and we have a blowout, though it was actually Iowa that averaged slightly more yards per snap over the course of the game (5.5 to 5.3); this was even more pronounced with Auburn and Carolina, which was a nailbiter to the gun despite a relatively large (5.7 to 5.05) per play disparity in Auburn's favor that would have led to a much wider margin if Auburn gets more plays. Notre Dame, too, did much the same to Penn State, though aided by more PSU turnovers earlier in the game.
Troy Smith: Cold-blooded clock killa
The game is still decided "per possession." But the fewer possessions, the fewer opportunities for one team to build a lead that will limit the options of its opponent; the smaller the sample size - in this case, "number of possessions" - the less likely larger trends - advantages and disadvantages in speed, size, execution, etc. - are to exhibit themselves. If you're not sure you can stop the other guy when he has the ball, it's best to keep the ball away from him. As long as the score remains within reach - which requires clock-milking offensive strategy and success on the part of the team trying to pull the keep-away - this is possible.