Kanekoa Texeira

Believe it or not, the Mariners have not used a left-handed reliever all season long. Conventional wisdom would have us believe that every bullpen needs a lefty or two to retire opponents' best left-handed bats in close games. But Mariners pitching coach John Wetteland is willing to challenge conventional wisdom.

"You don't need to have a lefty in the 'pen just because it's obvious that lefties do well against lefty hitters," Wetteland told MLB.com's Doug Miller last week.

Wetteland knows that as well as anyone. The righty allowed a .223/.292/.346 career line against lefty batters – not far from the line Wetteland allowed against righties. But not every reliever is as well-equipped to shut batters on both sides of the plate down.

To find out if Mariners GM Jack Zduriencik needs to add a left-handed reliever, let's see how the bullpen has done against lefties. Five weeks of data isn't much, so let's take a look at the numbers Mariners relievers have posted against lefties in their respective careers.

• Shawn Kelley – He has done much better against lefties in his career, limiting them to a .219/.268/.314 line.
• Sean White – His .219/.312/.322 line against lefties is quite good. However, left-handed batters are hitting just .225 on balls in play and homering on 4.5% of their fly balls against White. Both of those figures can be expected to rise and when they do, White's slash line will likely rise, too.
• David Aardsma – His .248/.363/.331 line is actually better than his line against righties.
• Kanekoa Texeira – Though Texeira has faced lefties just 26 times in the majors, his .208/.269/.292 line looks promising. Texeira struck out 106 batters in as many innings against lefties in his minor league career.
• Brandon League – His .284/.343/.453 line against lefties does not inspire much confidence, but League has allowed homers on 18.4% of fly balls against him and allowed a batting average of .321 on balls in play, which suggests he has been unlucky against lefties in his career.
• Mark Lowe – He has an ugly .298/.382/.514 line against lefties in his career. As Dave Cameron of U.S.S. Mariner noted earlier in the month, Lowe is "something of a glorified right-handed specialist." Lowe is now on the DL with an inflamed disc in his lower back.
• Jesus Colome – Lefties have hit .275/.382/.449 against Colome, so the Mariners should minimize his exposure to lefties.
• Ian Snell – Snell has allowed lefties to post a .294/.386/.484 line against him in his career. He should face righties whenever possible.

It turns out that Don Wakamatsu has more than enough weapons to retire opposing left-handers, especially now that Kelley's back on the team. But the Mariners have to use their 'pen carefully. Aardsma, Texeira and Kelley can succeed against lefty batters, but Colome, Snell and eventually Lowe should not face lefties in close games. The Mariners have their share of issues these days and their bullpen could be better, but Zduriencik can ignore conventional wisdom and proceed without acquiring a lefty.