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May 29, 2012

Sim Season Revisited

Filed under: Uncategorized — Bradford Doolittle @ 12:20 pm

I received an email from our good friends at Strat-O-Matic this morning pointing out something I should have rememberd. Last fall, we ran our Sim Season series as a partial remedy to basketball withdrawal brought on by the NBA lockout. In conjunction with Strat, we used their game engine and Kevin Pelton’s SCHOENE forecasting system to create the 2011-12 rosters, or at least the versions that existed at the time of the work stoppage. Then we ran the season game by game, and brought you the results on a daily basis.

Well guess what? The conference finals matchups forecast by Sim Season now look awfully prescient: Heat-Celtics and Thunder-Spurs. In other words, we nailed the NBA’s version of the final four well before we even knew if there would be a season. Okay, okay. There is some good fortune in that. The rosters across the NBA was markedly different than what they ended up as in the regular season. We had Chris Paul in New Orleans, Richard Hamilton in Detroit and lots of other players still in cities they ended up leaving. Nevertheless, we’ll score one for the simulation exercise, especially because most of us saw a Heat-Bulls matchup as inevitable and there weren’t a lot of people picking the Spurs to go this far.

We’ll have to try this again next year, though only in the aggregate. That daily thing was grueling …

May 21, 2012

A Note on Championship Leverage Index

Filed under: Uncategorized — Neil Paine @ 1:16 pm

I’ve used the concept of “Championship Leverage” a lot over the past year or so, but I realize that I’ve never really explained it very well. Here’s an attempt to correct that…

Championship Leverage obviously owes its name to the baseball stat invented by Tom Tango to measure the cruciality of a given base-out-inning situation. It starts with the win probability of each team in a series, given the current “state” of the series (home team in Game 4 up 2-1, road team in Game 6 down 3-2, etc.). The state of the series not only tells you how often each team can expect to win (assuming evenly-matched opponents with true .500 talent levels and a .600 home-court advantage), but also how much that probability can swing based on the outcome of the next game of the series, which in turn tells you the most important games in the series.

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May 10, 2012

In Defense of Coaches in the Playoffs

Filed under: Uncategorized — Kevin Pelton @ 12:24 pm

I had forgotten it was this time of year again. The playoffs being upon us, it’s about the point where fans and analysts alike lament that coaches that led their teams to successful regular seasons suddenly seem unable to coach. In the past, Oklahoma City’s Scott Brooks (the 2009-10 Coach of the Year) has been a popular target for this criticism. This year, it’s been applied to Lionel Hollins of the Grizzlies, who finished fourth in voting for Coach of the Year.

My suspicion is this line of analysis says a lot more about the level of observation than the coaches themselves. By any measure, this hasn’t been Hollins’ finest series. Too often, the Memphis offense has struggled to exploit the advantage Marc Gasol and Zach Randolph offer in the paint. Still, if the Grizzlies went through a stretch like this in February, would anyone outside of Memphis notice? Instead, during the playoffs, every available eyeball is glued to the game.
What troubles me, especially in the Twitter era, is that big-picture perspective is lost in favor of overanalyzing every individual decision in the playoffs. The great Bill James once wrote that the trouble with discussing organizations is that we pick out a handful of moves, good or bad, out of the thousands that each team makes. James was pointing out how easy it is to cherry-pick examples that fit a preset conclusion. Except in the case of Vinny Del Negro, I don’t think that’s the problem here, as people begin the process with the best of intentions. Still, I think James’ message fits.

Two issues exacerbate this problem. The first is that, much of the time, coaches are choosing between flawed options. Late-game offense is an excellent example. No matter what play is called from the sideline, teams aren’t going to score against a set defense that is completely locked in more than about 45 percent of the time, making it easy to second-guess any decision because we overstate the chances of scoring in the unknowable alterative. This only increases as the playoffs go on and the defensive competition gets tougher, making it increasingly difficult for any coach to succeed.

In addition, I think it’s possible there is a disconnect between the areas of coaching that get the most scrutiny and what really matters. Skills like player development and building a positive culture naturally get more attention during the long regular season than the crucible of the playoffs. Beyond that, even areas that are invisible to outsiders–like how well a team prepares in the film room for what it’s about to face–are evident during games only in terms of the results we see. As a result of this vacuum, in-game adjustments and moves are blown up into the entirety of a coach’s role, which is a dangerous mistake.

None of this is to say we should stop analyzing moves in real time, which would certainly be a hypocritical position for me to take. I merely think it’s necessary to add perspective to that commentary.

You can contact Kevin at kpelton@basketballprospectus.com. Follow his coaching criticism on Twitter at @kpelton.

May 7, 2012

Every Playoff Game is a Snowflake

Filed under: Uncategorized — Kevin Pelton @ 2:28 pm

So much of the time, we like to imagine that we can add results from the previous game of a playoff series, add in home-court advantage and player availability, and voila! An expectation for the next game. The Atlanta-Boston series is a reminder of the folly of such a philosophy. Let’s recap:

Game One: Hawks build a huge lead, then hang on for a win.
Game Two: Playing without Rajon Rondo, the Celtics steal a road a win as Josh Smith goes down with an injury.
Game Three: Despite Smith’s absence, Atlanta forces overtime in Boston before losing by six.
Game Four: The Hawks get back Smith and Al Horford … and lose by 22 after trailing by more than 30 points.

The moral of the story is there’s too much randomness within a single game to focus on one factor and expect it to regress to the mean. Every game is a unique environment. Sometimes, like in Utah-San Antonio, the results end up largely similar, but every game brings a new story all its own.

May 4, 2012

Underestimating the Base Rate

Filed under: Uncategorized — Kevin Pelton @ 12:04 pm

On the surface, transfers in the NCAA and injuries in the NBA don’t seem to have anything in common. However, I think there’s a pattern to the way we discuss both of them. What they share is that a widespread belief that they are increasing–I’d say it even reaches the point of conventional wisdom–isn’t backed up when we seek to quantify the two phenomena, as College Basketball Prospectus contributor Dan Hanner did yesterday in response to John Gasaway‘s question about transfers.

I think there’s a common explanation. When we think about issues like injuries and transfers (and coaching changes, to add another) in a non-statistical sense, I believe our default position is that they are outside the normal scope of basketball. That is, we imagine a world in which nobody ever gets hurt, or transfers, or gets fired, because these things happen relatively rarely. At the individual level, it makes sense to assume each player will be healthy rather than injured, or stay rather than transfer, but instead of adding the small percentages of each outcome, we just apply the same assumption to the entire group. So when change does occur, we perceive it as foreign and unnatural.

Think about it this way: Do you ever remember anyone observing that injuries are down relatively to some other period? Maybe this happens at the team level, like with the Suns, but I don’t think it happens with anywhere near the frequency of people lamenting the increased prevalence of injuries. When injuries don’t occur, it’s invisible because that’s what’s supposed to happen. Same with a college team that doesn’t have any transfers and brings back the same group of players, minus seniors and early entrants.

As a result, it’s easy to underestimate how often these rare events happen. Whenever we do hear about a lot of them at the same time, it tricks our brains into thinking this is more unusual than it really is. So we often perceive injuries and transfers as happening at an increasing rate, when really nothing has changed.

You can contact Kevin at kpelton@basketballprospectus.com. Follow him on Twitter at @kpelton.

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