Archive for the ‘Liverpool’ Category

Norwich City v Liverpool - Barclays Premier League

Liverpool Football Club has worked diligently all season toward their first league title since 1990. Now, at the end of April with the team on 80 points, five ahead of Chelsea, it is realistically within their grasp. Should they win the prize that many couldn’t over the past two and a half decades, they will have earned every last inch of the trophy.

Even so, Liverpool’s triumph will have been aided heavily by some fairly unsustainable numbers, numbers which should spur Brendan Rodgers to action in the club’s off-season.

On the surface, Liverpool’s dominance is something a statistical outlier (“That’s cuz those numbers don’t explain passion and romance! etc. etc.”).

Why? Well their shots ratio, which has held steady most of the season, is ranked 5th in the Premier League (for an explanation of all these concepts, read this piece).

Meanwhile Liverpool’s PDO (sh% plus sv%, a measure of good luck when well above the median of 1000 and bad when well below) is high but not screamingly high at 109.47 (thanks Ben).

At first glance, it’s difficult to see where Brendan Rodgers is getting his secret sauce. Taken together, based on how well TSR correlates with points (and how quickly PDO regresses to the mean), these numbers shouldn’t really put Liverpool top of the table on 80 points with three games to go. This is a low probability event.

I’ve posited before that Game States might hold some of the answer. LFC spend a lot of time winning, which means a lot of time at at least a +1 game state. What does that mean? Well teams at +1 tend to take fewer (but generally more accurate) shots and concede more, which would in theory lower their overall TSR. Yet Man City have spent even more time winning than LFC and their TSR is sky high, commensurate with a first or near first finish.

Maybe that’s because City build up leads, which tends to diminish the GS effect (at +2, things start to revert back to normal). Or maybe City’s TSR is skewed by a small number of games in which they wildly outshot inferior opposition.

Maybe though something else is going on, and this is where we arrive at this pair of tweets from James Grayson which I nearly missed yesterday, but that carry a difficult truth for Liverpool FC.

Shots on target percentage is exactly what it says it is—the percentage of total shots which are on target, for and against. You can measure this percentage against your average opposition SoT%, and come up with a differential. Liverpool’s is evidently quite high.

Why does this matter? Well as Grayson worked out last year, SoT% is roughly split between luck and skill. As Grayson notes in the second tweet, In Liverpool’s case it would explain why a team with a mediocre TSR and a not-that-high PDO is rocking it in first place.

The temptation in Liverpool’s case would be to look at LFC’s very high SoTF% and their very low SoTA% and conclude, “It must be something Brendan’s doing on the training pitch.” This was my line of thinking yesterday when I speculated on why LFC’s differential is so high.

Yet this would only make sense if SoT% for and against was consistent at the team level year over year. So then, here’s the bad news, at least as far as next season is concerned:

In other words, their SoT%s are going to regress. And if LFC post a similar TSR and PDO next season but with a much lower SoTF% and SoTA% differential, they likely won’t finish near or at first place.

Does this mean Liverpool aren’t worthy of their Premier League trophy, should they win it? Of course not. You win it on points, not on abstract probabilities.

What it does mean is that the team should consider seriously strengthening their squad ahead of next season.

Regression is never a popular subject in sports, let alone football. No one wants to believe their team is winning on the back of random variation. We want everything on the pitch to be explainable, even if we know, like all football-loving folk, that luck plays a big role from game to game, hence the mantra about championship teams winning matches “they should have lost.”

Liverpool will deserve their PL trophy, should they win it. But they shouldn’t fall prey to complacency. Look what it did to Moyes’ United.

Liverpool v Tottenham Hotspur - Barclays Premier League

Resident hockey expert Justin Bourne wrote a stellar piece on “score effects” in hockey this morning. Here is a good definition of score effects via the popular Toronto Maple Leafs blog, Pension Plan Puppets:

Teams that are behind tend to get more shots and scoring chances because they press to get back into the game, and often the team with the lead naturally sits back and absorbs pressure. Conversely when the game is tied, or close (within a goal, or within 2 in the 3rd period) teams tend to play a much more balanced approach, giving up as little as possible, and working to score more goals on offense.

Interestingly, this effect persists in soccer too where it’s generally referred to as ‘game states’.

Bourne offers up a few theories for the root cause of this effect in hockey. One in particular however stood out for me: simple psychology. When their team has a lead, coaches tend to put out less talented players and their more talented players are under greater pressure to avoid mistakes:

What they do want, is Jay McClement to chip the puck out of the zone because, like fans, they’re less stressed when the puck isn’t in their zone. So, it gets out, coach feels relief, sees who made the clear, and the rat has been rewarded. He wants more of that.

If we were a behavioral psychologist, we might refer to the psychological response to the scoreline as a kind of heuristic. To borrow the Wiki definition:

In psychology, heuristics are simple, efficient rules, learned or hard-coded by evolutionary processes, that have been proposed to explain how people make decisions, come to judgments, and solve problems typically when facing complex problems or incomplete information.

Now I’m bending the rules a bit here, but in soccer, game states are a persistent effect, to the point where there is clearly something going on which goes beyond conscious tactical adjustment. I haven’t conducted a study but I’m inclined to think the persistence of score effects/game states underscores a fairly natural team response to a lopsided scoreline.

Anyone who’s ever played a team sport knows it. You’re losing, your team gets desperate, you all push up the pitch to try to get back in the game, and in doing so you leave yourself open at the back. You see it in football matches all the time.

Now in behavioral psych, heuristics become interesting when they lead to cognitive biases: decisions that feel right but are in fact ‘illogical’ (not to sound too much like Spock). If you’re aware of this pitfall, you can use it to your advantage either by avoiding it yourself or taking advantage of it in others.

And this where we get to Brendan Rodgers’ 2013-14 Liverpool FC.

They are league leaders on 71 points and the talk of the league, playing a breathtaking, attacking style of football that puts asses in the seats. Great stuff for the neutral.

Some, like Michael Cox on yesterday’s Guardian Football Weekly podcast, point to Liverpool’s incredible counterattacking ability. That view fits with some telling statistics courtesy of the great and vital work of Ben Pugsley.

First, a primer on some advanced stats in soccer.

Liverpool are third overall in the Premier League behind Man City and Arsenal in TSR at a tied Game State, but are eighth in TSR Close (which included tied and +1 Game States). Moreover, Liverpool shoot once per 11 passes, the second smallest ratio in the league (they’re behind Newcastle).

From this we can glean a few possibilities. At a tied game state, Liverpool are effectively dominant, outshooting their opponents and pushing for an opening goal. However, we can safely assume that Liverpool are spending a good amount of time at +1, which is when the losing side tends to push up the pitch and take more shots, opening up space behind them which a quick attacking force of the likes of Sterling, Sturridge and Suarez can take ruthless advantage. The speed of Liverpool’s transition to attack could also be reflected in their very low passes-to-shots ratio.

Now you don’t need statistics to tell you the advantages of working hard to score the first goal, then sitting back to play aggressively and quickly on the break. But Liverpool’s approach also neatly fits with a statistically consistent, apparently universal predictable pattern of play observed in Game States.

It’s also clear that many top tier teams don’t adjust their play to take advantage of the Game State effect, for example relying on plodding build up play allowing the opposition defense to track back in time to defend in numbers.

Now I don’t know what kind of data LFC and Rodgers tracks, but here is a clear area where a coach can take a statistically measurable effect like the Game State heuristic, and use it to their advantage. See? Analytics in action, and you may not have even realized it.

Liverpool's Sturridge celebrates with teammates Gerrard and Henderson after scoring a goal during their English Premier League soccer match against Sunderland at Anfield in Liverpool

 

Devang Desai, Richard Whittall and James Bigg sit down to talk about another Manchester Derby dominated by City, the future of Arsene Wenger at Arsenal and Bayern Munich’s latest triumph.

You can download the podcast here and subscribe on iTunes here. You can also find the RSS Feed here.

Despite Suarez’s now official request to leave Liverpool, as he acknowledged an actual move could theoretically fail to happen, which invites the interesting possibility he may spend at least half a season more with LFC.

How would Liverpool fans respond? The player has always received full support from the club during his most trying moments, particularly during the Patrice Evra affair. Would he spend four months on the bench? For a lesser light in a deeper squad this could play out, but Suarez is considered Liverpool’s most important player.

If he’s a regular starter and is again the subject of controversy, will he still be a “Liverpool legend” and receive full backing from the Kop?

In any case, at least one fan has already picked a side.

FBL-WC2014-URUGUAY-TRAINING

He was speaking in an interview with GolTV’s Martin Charquero apparently. He often spins this kind of crap while on international duty however, and this may be nothing more than a case of having a nice whinge while on vacay.

But he does have a point: it was the English press that bit Ivanovic and the English press that repeatedly contradicted itself when giving its defense in Patrice Evra’s racial abuse case.

My goodness, it’s a twofer! Must because with the title decided and Wigan basically set to go down, it’s just starting to “hot up.” Anyway, Liverpool vs Everton above, and Man United vs Chelsea below. If you want to be cool and follow the floating heads on Twitter, it’s @amhrichardson and @iamthemonkey.

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Are you a bored partisan plebe who has nothing better to do in their spare time than mull over FA arguments in search of inconsistencies as proof that England’s Football Association is corrupt, hates your club and your club alone, and wants Luis Suarez to die because he’s Uruguayan and because Liverpool must be prevented from ever winning the Premier League again?

Here you go.