GRAND CENTER — A year ago, Houston starter Wandy Rodriguez allowed 22 home runs, but only three of them were to lefthanded hitters. One was by Chris Duncan.

Could be a reason why tonight manager Tony La Russa decided was the night for Duncan to make his first appearance in the starting lineup since opening night.

In his career, Rodriguez has proven equally difficult against lefties and righthanded hitters when it comes to batting average. The biggest difference is in the slugging, where righthanders score a .461 against Rodriguez in his career and lefties are .411. In 2007, here’s what lefties hit against Rodriguez:

.252 BA/.301 OBP/.370 SLG … 3 HR in 137 Plate Appearances.

Duncan, meanwhile, has been successful against Houston and particularly at Minute Maid Park. It’s likely the confluence of all these numbers and his health that has Duncan in left field tonight. Here are Duncan’s numbers coming into tonight’s game against Houston and at the ballpark formerly known as Enron:

vs. Houston … .321/.429/.660 … 18 games … 4 HR, 10 BB, 16 K

at Minute Maid … .306/.390/.694 … 12 games … 4 HR, 5 BB, 13 K

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This game is being played at a breathless pace. Can barely keep up.

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Todd Wellemeyer, ever questing to keep his pitch count under control, just had an eight-pitch fifth inning. He came into tonight’s start average 19.00 pitches per inning or six more per inning than Adam Wainwright. Wellemeyer needed 6 1/3 pitches per out in his first start of the season. … And he K’s Hunter Pence with his 74th pitch.

Or an out every 4.11 pitch.

With his next out this is the longest start of Wellemeyer’s big-league career.

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