By the Numbers: Tall tale of two halves

In the days just before and after the All-Star Break, it's the time of year when one of baseball's favorite myths gets its toughest workout. These are the days when we hear and read about who the great first-half players are and who the great second-half players are. Depending on how your players have done in the first half, these labels can be a source of either hope or trepidation. If you have Robinson Cano, you remember that he came on like gangbusters in the second half last year, so you hope maybe he's just a "second half" kind of guy. Or you are trying to decide whether to keep Gerald Laird on your roster until he is activated from the DL, and you remember his stats fell apart during the dog days a couple of years ago. You toss him onto waivers before he does any second half damage.

The problem is that neither of these players has a trend for being a "one half" player, just a single uneven year that stands out. At least in recent years, there aren't many cases of so-called "first half" or "second half" players. Of the 25 full-time position players who have the largest gains in RC/27 scores over last year -- in other words, potential "first half" players -- only four were substantially more productive in the first half than in the second half in both 2006 and 2007. There are even fewer players who have consistently underachieved in the first half. Of the 25 regulars with the biggest drops in RC/27 scores since last year, only two were "second half" players in both '06 and '07.

This data alone doesn't tell us much about whether a player really performs better during some months of the season than in others. However, aside from demonstrating that there are very few players who are even potential "first half" or "second half" players, they provide us with the basis for an analysis to see why some players may produce more during certain parts of the schedule. In the breakdown that follows, we will look at each of the six players who are in line for a third straight uneven season. For each player, we will compare their overall productivity by half season, as measured by OPS. We will also look at splits for three skill indicators: walk rate, whiff rate and Isolated Power. This way we can see if these players have had their typical first halves and if there is a pattern to their second half comebacks and collapses.

Potential First Half Players

Jason Giambi, 1B/DH, New York Yankees: The odd thing about Giambi being a potential "first half" player is that this year he was abysmal for the first six weeks of the season. A torrid two months brought Giambi back in line with his usual fast-starting ways. Given his inconsistent performance during this year's first half and the lack of an overall skill pattern the previous two seasons, it doesn't look like Giambi is a true "first half" player. In 2006, a drop in power was responsible for his late season slump, while in 2007, a huge spike in strikeouts was to blame. With this mixed bag, it's anybody's guess as to how Giambi's season might progress from here on.

Jose Lopez, 2B, Seattle: In Lopez' first two seasons as a full-timer, he played well enough to belong on a mixed league Fantasy roster. At least this would be true if Fantasy leagues closed shop sometime in July. After the All-Star Break, all semblance of power disappeared for Lopez. From a productivity perspective, Lopez turned in a typical first half this year. Skill-wise, he made more frequent contact but hit with a little less power. His power has held up in June and July, but owners should be wary of Lopez in the second half. His power comes primarily in the form of doubles, so any extended doubles drought could be a sign of another long second half.

Casey Blake, 3B, Cleveland: Despite huge dropoffs each of the last two years, Blake is not a strong candidate to be labeled as a "first-halfer." Despite having an RC/27 to date that is more than a run higher than last season's, he is not off to one of his faster starts. Also, Blake had a better second half than first half in both 2004 and 2005. The one constant over each of the last four seasons is a large decrease in walk rate after the All-Star Break, but unless it is coupled with a dropoff in power, a similar decline in walks this year would not be likely to have much of a Fantasy impact.

David DeJesus, OF, Kansas City: While a second half decline in performance has been evident for DeJesus in each of the last two years, the first and second half skills trends are all over the place. Since DeJesus' late-season falloffs don't appear to have a basis in a sagging skill base, maybe fluctuations in H/BIP are responsible. Sure enough, his rate dropped seven percentage points in the second half last year and three points the year before. Some of that can be tied to modest declines in power, but some is probably random. There is simply not enough of a trend in any area here to brand DeJesus as a sure-fire second-half decliner.

Potential Second Half Players

David Ortiz, DH, Boston: If Big Papi isn't a "second half" player, then there is no such thing. He has hit with more power in the second half every season since coming to Boston in '03. In the last five seasons, there has been only one year in which Ortiz's Isolated Power increased in the second half by less than 0.045. In each of those years, he has had a higher OPS in the second half as well. Perhaps Ortiz's recovery from his wrist injury could change this trend, but if you own him, make sure you activate him for next week, if you haven't already. If you don't own Ortiz, his slow start, DL stint, and strong second half track record make him a great "buy low" target.

Ryan Howard, 1B, Philadelphia: In 2006, Howard saw dramatic improvement in the second half based on gargantuan increases in power and walks. Last year, his post-Break gains were much less dramatic. Maybe the surge two seasons ago was the result of a player figuring things out in his first full season as a major leaguer. Howard is likely to rebound, just because his first half stats are too much of an aberration from what he has accomplished over the last two years. Unless his '08 second half gains are substantial, there is too little data here to mark Howard as a "second half" player.

The players reviewed here represent those who would be most likely to be true "first half" or "second half" players, yet at most, only two of them genuinely deserve the label. Jose Lopez has performed much better before the Break in his young major league career, while David Ortiz has a consistent track record of picking up his pace after the Break. With the possible exception of these two everyday players (pitchers could be another story), there seems to be little to no support for the first half/second half myth. When evaluating roster moves for the second half, don't worry about a player's pre- and post-Break splits. Their long-term full-season trends are still the key to projecting future performance.

Al Melchior was recently a Fantasy columnist and data analyst for Baseball HQ and will be providing advice columns for CBSSports.com. Click here to send him a question. Please put "Melchior" in the subject field.