This saturday, relegation-threatend Fulham host Liverpool in what is always one of the toughest fixtures of the season. Throughout the season, defense has been a clear weakness, particularly the centre-backs. Nine different pairings have seen time so far, and like many supporters, I have had difficulty keeping track of which ones are most effective.

For the most part, centre-backs are not relied upon for their offense. You may see them go forward for set pieces, or make long passes up to a forward, but for now I'm going to ignore the offensive aspect of their game. In most sports, players with a defense-only role are measured by how many "points" they allow per game. In baseball, a pitcher's earned-run average tells us how many runs he would allow over 9 innings. A hockey goaltender's goals-against average tells us how many goals he allows over 60 minutes of play. In football, similar statistics are kept for goalkeepers, but why can't we judge centre-backs the same way?

I went through each of Fulham's matches, looked at which centre-back pair (or in some cases, pairs) played, how many minutes, and how many goals conceded. I then added up the numbers for each pairing, divided the goals against by minutes played, and multiplied this number by 90 minutes. Here are the totals:

Ian Pearce has been effective, but may not play again this season

Elliot Omozusi is a good prospect, but a 66-minute sample is obviously not enough to name a player to the starting XI. The second pairing, Carlos Bocanegra and Ian Pearce, is more intriguing. Although they haven't played as many minutes together, the pair has been extremely effective, and with a GAA much lower than any other pairing. Their three full matches together were all in March, against Aston Villa, Wigan, and Pompey. Perhaps even more impressive is the number of shots allowed - opponents managed only 28 shots in those 3 games.

Unfortunately, we may not see this combination again. Ian Pearce has been out for several weeks now with a foot injury. physioroom.com lists his expected return date as May 5th, but even if he is healthy by then, it will take some time to get him up to match fitness.

Eliminating all of Pearce's pairings, the clear choice for Saturday's matchup with Liverpool becomes Carlos Bocanegra and Philippe Christanval. This pair, who helped Fulham to a clean sheet in one-third of their matches this season, has been considerably more effective than the next-best option of Christanval and Zat Knight. Lately, Bocanegra has seen time filling in for the injured Franck Queudrue at left-back, but Liam Rosenior was used previously, and his pace may be more useful at that position. Sliding Rosenior from the right side to the left also opens up a spot for Moritz Volz, a solid two-way player who brings a more attacking presence to the position.

I didn't include full-backs in this analysis for a couple reasons. First, full-backs are expected to get forward in attacks a lot more than centre-backs, so judging them solely on goals conceded wouldn't be a fair assessment. Second, and this just happens to be the case for Fulham, the team's options at the position aren't nearly as great. Liam Rosenior has had a majority of the starts at right-back, and Franck Queudrue has seen most of the time on the left. With Queudrue's injury, Rosenior had initially shifted over to the left side to make room for Volz, the only other Premiership-experienced right-back on the squad.

Here's my back line for Saturday:

LB: Rosenior
CB: Bocanegra
CB: Christanval
RB: Volz

The way I see it, Fulham has 5 players vying for 4 spots: Bocanegra, Christanval, Knight, Rosenior, and Volz. Of these, Zat Knight is the inferior player, and should remain on the bench. To accommodate for the rest of the players, Rosenior should move to left-back, allowing Bocanegra to play along side Christanval in the middle.