Conceding Halftime Leads in the Premier League: Why Arsenal’s Collapse Against Tottenham was a One-In-Forty Occurrence

You should be angry, Arsene!

Just how rare was Arsenal’s second half collapse against Tottenham Hotspur on November 20^th?  Sure it was Tottenham’s first victory at the Emirates, and its first win as the away team in this fixture in seventeen years.  Teams come and go in the Premier League as do players, so I don’t put much stock in such streaks.  The better question to ask is how rare was this collapse when looking at historical averages.  Chris Anderson from Soccer By the Numbers has been kind enough to supply the data behind his recent post on halftime leads and fulltime results (EPL seasons 05/06 through 09/10), and the results do indeed make Arsenal’s collapse look like a very rare event.

First, let’s look at all results without declaring if the team that is ahead at halftime is home or away and whether or not they went into halftime with a clean sheet.  This produces the table below.

The rows on the left indicate the halftime lead, and the columns across the top are the full time result.  The results for a halftime lead of 2 goals indicate that regardless of location or a halftime cleansheet, historical data indicates that Arsenal had a 95% chance of winning, a 3% chance of drawing, and 2% chance of losing.

Taking the analysis one step further, the data set is isolated for leads at home to produce the table below.

In examining this result, Arsenal as the home team still had a 95% chance of winning, a 2.5% chance of drawing, and a 2.5% chance of losing. It turns out that further reducing the data for a cleansheet while at home does not change the numbers for a two goal lead.  Nonetheless, the table below is provided for those interested in other clean sheet halftime leads and their results.

Ultimately, this means Arsenal’s loss was a one-in-forty occurrence given their two goal lead at home with a clean sheet at the half.  Even without Kabul’s winning goal in the 86^th minute Arsenal would have still experienced a one-in-twenty collapse in conceding a draw with such a halftime advantage.

Of the other four such collapses the last five seasons, one team features twice and each of the two teams in this latest occurrence play a role in the other two matches.

First, Manchester City experienced such a fate twice in one calendar year.  The first time, April 26^th 2008, saw City go ahead 2-0 in the first twenty one minutes, only to concede three goals in the final twenty one minutes of play against Fulham.  Liverpool then repeated the feat of overcoming a 0-2 Man City lead on October 5^th, 2008 with Torres and Kuyt keying the Reds’ comeback.

West Ham United experienced a similar collapse against none other than Tottenham on March 4^th, 2007.  Carlos Tevez contributed to the 2-0 halftime lead, while Tottenham battled back even by the 63^rd minute.  This match was the only one of the four where the team leading at halftime subsequently took the lead again after relinquishing it in the second half, all off a Bobby Zamora goal in the 85^th minute as a substitute.  Tottenham then battled back with two goals in the final minutes, including the winner in the 6^th minute of stoppage time.

Ironically, Arsenal played the roll of spoiler in the fourth-and-final match as they came back on Bolton on March 29^th, 2008.  Not only did the Gunners embarrass Bolton on their home pitch, but they did so down a man the entire second half.

It seems as if Arsenal is in rare company, having been on both ends of such an event.  Tottenahm is also in a rare position, having won two of the five occurrences.  I doubt any of the other collapses were as painful for those teams as Arsenal’s collapse in the latest iteration of the North London Derby.