Roger Clemens, the winningest pitcher alive and still an ace at an age when most ballplayers are selling cars, recently stood up in George Steinbrenner's box at Yankee Stadium, like Mussolini at the balcony, and told a cheering crowd that he was coming back to the Yankees. New York sports being New York sports, the muttering started a half-second after the cheering. Did the Yankees just buy another pennant? Or another Kevin Brown? Is Clemens really worth $18 million?
The question has been chewed over in the sports media since the announcement. But what's been missing from the debate is the quantitative question at its base. Four months of Clemens is worth a certain amount to the Yankees. How much?
Let's break it down. First of all, how much money is a playoff berth worth to the Yankees? According to the late baseball statistics guru Doug Pappas, the Yankees' postseason revenues in 2001, a year they made it to the seventh game of the World Series, were $16 million. So, even if we assume that a Rocket-fueled Yankees team will go all the way, Clemens still might not pay back the Yankees' investment.
Of course, fielding a contending team puts more rear ends in the seats during the regular season, too: If the Yankees finish fourth this year, don't expect sellouts for next year's weekday homestand against Kansas City. Revenues coming directly from playoff games don't tell the whole story—there's a value to just being in the hunt, even if Yankee fans of the "nothing but a ring will do" variety won't admit it.
Luckily, Nate Silver has come up with a computation of the cash value of adding wins to your regular-season record. That value depends on which wins you're adding: Going from 56 wins to 62 is worth much less than going from 90 (wild-card contender) to 96 (probable division winner).
So, where are the Yankees starting from? That is, how many games would they win without Clemens? My go-to source for real-time predictions of this kind is Clay Davenport's postseason odds page. His projection uses a so-called Monte Carlo system, which means it operates by running simulations of the baseball season again and again to see, on average, what happens. Every day, starting from that day's standings, his computer runs through 1 million fake seasons, making a best estimate of the odds of each team winning each game. As of this writing, he has the Yankees winning an average of 86.6 games and making the playoffs 36.6 percent of the time. (At the outset of the season, before the Bombers' current struggles, those numbers were 90.8 games and 52.6 percent.)
Starting at 86 or 87 wins is just when extra victories become really valuable: According to Silver's computation, it would take just four extra wins in the Yankee ledger to make the $18 million payout to Clemens a black-ink transaction. Surely the Rocket's going to win four games, right? But that's not the question. He needs to win games the Yankees otherwise wouldn't have won.
Pitchers win games by preventing runs. To determine whether Clemens will help the Yankees win games they would have lost without him, we need to know how many runs Roger Clemens will deny the Yankees' opponents.
If he suits up at the beginning of June, Clemens is likely to make about 23 starts. At his current age, he's averaging just under six innings a start. So, let's say he'll throw 130 innings. Clemens' ERA last year in Houston was a sterling 2.30, best in the National League. His numbers won't be that gaudy in the offense-rich AL East (in his last three years in New York, he posted ERAs of 3.51, 4.35, and 3.91), but there's every reason to expect him to be effective. The most popular baseball prediction systems project Clemens to have an ERA between 3.00 and 3.50 as a Yankee. That means he'd allow between 40 and 50 runs over the course of those 23 starts.