Projections versus Past Performance

added 3/6/2008 by Scott Barzilla

Yes, we all know I like numbers. Numbers when they are put in the form of projections tell us a whole lot about what someone thinks. A picture paints a thousand words I guess. Last time, I talked about how Baseball Prospectus (BP for short) really took the Astros down a peg this winter. Just a quick look at Value over replacement player (VORP) really drives this point home.


Chicago Cubs       412.1
Milwaukee Brewers  400.1
Cincinnati Reds    365.9
St. Louis Cards    329.3
Houston Astros     316.7

No, I did not include the Pirates because even BP wouldn't stoop to the level of putting the Bucs in front of the Astros. How do we convert this into a useable number? The great minds at BP have done that and project the Astros to finish with a similar record as last season. It leads one to wonder why the club went for broke this winter if everything looks so bleak.

This is where we have to look at the difference between projected performance and past performance. If we take the same rosters each team has currently and simply insert their 2007 VORPs then we see an entirely different look in the standings. You can even begin to see what Ed Wade and company are thinking.


Chicago Cubs       457.2
Milwaukee Brewers  402.5
Houston Astros     385.1
Cincinnati Reds    368.2
St. Louis Cards    270.8

So, what does this all mean? For one, we should note that the five teams fell on an average of three percent from their past numbers to their projected numbers. This is more or less normal. Most teams will see performance drop as players age. Occasionally, teams that go with youth movements will see that improve. The 2008 Cardinals are a good example of this, and I'd imagine the Bucs would be another example if we included them. The Astros dropped 18 percent. That's certainly a titch more than three percent.

If we give the Astros the same three percent drop then they would still be in a close race with the Reds for third place (375). However, it should be noted that the other four teams did not see a drop off collectively when the Astros were removed. All of these numbers are telling, but when we break down the numbers to their individual parts we see more.

BP does not think a whole lot of Kaz Matsui or Michael Bourn. Both played in hitter's parks in 2007, so switching to the neutral MMP could kill their numbers. Yet, it could also be argued that Bourn will play well with regular play. One could argue that Matsui has turned a corner. If those two produce as they did in 2007 then the team will be a lot closer to producing 2007's actual numbers.

On the mound, BP predicts a dip for Roy Oswalt, but they are not alone there. Oswalt's strikeout rates have fallen in recent years. Most projection systems rely on the work of Voros McCracken (DIPS) and strikeout rates are paramount there. Yet, Oswalt has continually defied the odds before. If he defies the odds again we will see the Astros come even closer to that level.

Still, the Astros won't get all the way back. Lance Berkman, Carlos Lee, and Miguel Tejada are all a year older and not a year better. Doug Brocail and Woody Williams are on the wrong side of forty. Their presence's indicate an overreliance on single year evaluations. Brocail had the look of a world-class setup man last year. He won't be one in 2008 unless we are really lucky.

These projections have their place in the analysis industry. I'm looking forward to seeing what The Hardball Times has to say next week. As Clack said on the bulleting boards, if you take multiple projections together (Marcel, CHONE, Bill James, Ron Shandler) then you will get an idea where you team really is instead of just where they were.