Determining who's going to bat lead-off is generally one of the most significant decisions that a manager has to make while filling out his lineup cards. The lead-off man is the first player to step up to the plate for your team each day, right in front of the club's vaunted sluggers. And more importantly, being at the top of the order means getting to the plate more often. So no, this isn't the same as arguing about whether Yuniesky Betancourt or Wil Nieves should be batting eighth.
Delving into some lineup optimization theory, according to research done by Tom Tango, Mitchell Lichtman and Andrew Dolphin in The Book, a team should deploy their two best hitters in the No. 2 and No. 4 spots in the lineup, with the third-best hitter going No. 1. So generally speaking, when you're talking about any given lead-off hitter, you should be talking about one of the best hitters in the lineup. But that's not always the case, as traditional lineup construction previously emphasized batting average and speed at the lead-off spot in favor of on-base percentage, which has proven to be the ultimate marker for evaluating lead-off hitters. Sky Kalkman wrote a great piece for BtB a couple years ago that explains The Book's tips for lineup construction in detail if you're interested.
Getting back to the task at hand, though, is the reality that many teams don't properly utilize the first spot in their batting order. Some teams are still emphasizing the old-school hit/speed combination from that spot, and others just seem to assume that anyone with power shouldn't be hitting at the top of the order. And while it's true that lead-off hitters see less PA's with men on base compared to other spots in the order, the reality is that regardless of whether your lead-off hitter is fast or powerful, there's one skill that he should absolutely have, and that's the ability to get on base.
Take the Cardinals, for instance. They've been primarily using shortstop Ryan Theriot in the lead-off spot, presumably because he's batted .282 with 23 steals per season over the past four years. But realistically, this guy shouldn't be anywhere near the top of St. Louis' batting order. Outside of a 2008 season when he pushed his walk rate up to 11%, it's been in the 6-8% range in three of the past four seasons- with such little power, he needs to walk more than that if he wants to be effective from the lead-off spot. He's done it before, but at age 31 he doesn't seem likely to push his walk rate back up from 6.4% in 2010 to near 10-11% in 2011, and he's never had any power anyways. With such a strong 2-3-4-5 in Colby Rasmus, Albert Pujols, Matt Holliday and Lance Berkman, Theriot sticks out like a sore thumb at the top of that order.
Or look at San Diego's usage of Will Venable in the lead-off spot. Venable is nothing like Theriot- he's got some power, he takes tons of pitches, and his biggest issue is a long swing that leads to lots of strikeouts. So why exactly is he batting No. 1 for the Padres, even though practically every projection has him hitting roughly .250 with a .320 OBP? It probably has something to do with the 29 bases he stole last season. Why not try to take advantage of Venable's power potential and swap him with current No. 3 current Orlando Hudson and his .347 career OBP?
Toronto seems to be making a similar move by putting Rajai Davis in front of Yunel Escobar. Davis is considered a prototypical lead-off guy because of his high-contact approach (.279 BA, 16.6% K%) and base-stealing skills (91 steals in 2009-2010). But outside of a .360 OBP in 125 games two years ago, he's never had the on-base numbers you want from a lead-off man. Meanwhile, shortstop Yunel Escobar has a .366 career OBP, and he's generally been hitting second. Why not slide Escobar up to No. 1 in the order, push Travis Snider up to No. 2 and push Davis down to No. 9, following the "double lead-off hitter" theory?
There are other examples, too. Detroit using Austin Jackson at No. 1 in the order when he's highly unlikely to repeat last year's .345 OBP. Kansas City batting Mike Aviles at the top of the order even though he's never had a walk rate above 5.6% at Triple-A or in the majors (Author's Note: Apparently the Royals have pushed Chris Getz up to the top of the order. He's not great either, but he'll walk more than Aviles). There's Ian Desmond in Washington, too.
We've made a lot of progress in optimizing batting orders over the past few years, particularly in terms of our understanding of what makes for a good lead-off hitter. But it's worth remembering that in the end, using the worst possible lineup one could put together instead of the best one, one would still only be costing their team a win or two over the course of the season. So while it's pretty irritating to see Ryan Theriot come to plate more often than Albert Pujols, they're only shooting themselves in the foot a little.