LAS VEGAS -- It's good to have a lefty or two, all other things being equal. But it's bad to overpay for one. And besides, all other things are rarely equal.

When the Yankees agreed to a seven-year $161 million megadeal with free agent left-hander CC Sabathia, it marked the third consecutive winter that a left-handed former Cy Young winner has come to terms on an enormous contract.

In December of 2006, Barry Zito signed a seven-year contract with the Giants, including an option for an eighth season, worth a guaranteed $126 million. And just before this year's Super Bowl, the Mets traded for Santana and inked him to a six-year deal with a club option worth a guaranteed $137.5 million.

Now, the Yankees have reeled in Sabathia with the richest pitching contract of all time. And it's no coincidence that that deal went to a lefty. Whether it's true or not, many in baseball believe that you simply have to have a left-hander, and that there's more value to a lefty starter than a right-hander.

But in the end, it's not about which hand you throw with -- particularly in an era of five-man rotations where starters are rarely re-jiggered to maximize matchups. It's about how good you are, and in terms of contracts, how good a bet you are going forward.

Even in October, it's rare to see a team shake up its rotation for left-right reasons. In recent years we've seen decisions on playoffs made based on home-road splits and even day-night splits. But it's extremely rare lately to see a team sub in a pitcher for another pitcher based on a left-right difference. The best pitchers pitch in October, which should tell you a great deal about how things go the rest of the season as well.

Two years in, the Zito deal looks like a disaster and it's hard to envision how that perception could change. Zito, though he was just 28 when he signed with San Francisco, had already fallen off in his last couple of years in Oakland as compared to his breakthrough campaigns in 2001-2002.

But Zito had the wins. He had the Cy Young Award. And he had the trump card -- he's left-handed.

Hot Stove

Before that offseason hit, the Astros locked up Roy Oswalt to a five-year, $73 million deal. Oswalt was in the midst of a much better 2006 season -- lower ERA, more strikeouts, fewer walks. His year-by-year trends were better. He'd never won a Cy Young, and he's 10 months older, but in late 2006, there was virtually no doubt that Oswalt was a better pitcher than Zito.

Surprise, surprise -- even in Oswalt's "off" '08 campaign, he was the superior pitcher at the lower cost. Admittedly, Oswalt never hit the open market, which is a major difference between the two contracts, but the contrast is striking just the same.

Despite the move to the friendlier league and a pitchers' park, Zito's performance keeps heading in the wrong direction, and his statistical indicators show that it's not likely to get better. And the fact is, if a seven-year deal doesn't look good in Year 2, it's quite certainly not going to look good in Years 6 and 7.

That's the risk with evaluating deals like this. The knee-jerk reaction when a newly signed player has a big year is to praise the deal. But it's expected that these guys will be good right away. If that weren't the case, they wouldn't have been in line for the contract in the first place. It's the later years where some contracts become albatrosses.

And if a team overpays, relative to a pitcher's ability, because it wants a left-hander, that outcome becomes even more likely.

What the Yankees are hoping is that they've made an acquisition more akin to their crosstown rivals' move back in February. The Mets didn't just pick up a lefty. They picked up the best pitcher in the game. Santana's value is his performance, not his handedness.

Not coincidentally, Santana's deal looks excellent -- at least after Year 1. He was third in the voting for the National League Cy Young, the fifth straight season he's ranked in the top five in the balloting. Some of his peripheral stats dipped a little, but he has so far to fall before he's merely excellent that that's OK.

The evidence suggests that what the Yankees have acquired is something in between. Sabathia had his best year in 2008, and it was about in line with a typical Santana season. Sabathia's typical seasons are certainly better than Zito's typical seasons, but not up to a normal Santana campaign.

So is Sabathia being paid because he's a lefty? If so, probably only a little. He had the good fortune of being the best-regarded pitcher, coming off a dazzling four months of pitching, in a winter when the Yankees were going on a spending spree.

In the short term, he's very likely to make the Yankees a better team. He's a tremendous pitcher. But it's not the fact that Sabathia throws left-handed that makes him a plus. It's the fact that he's durable and effective.