The A’s visiting the Astros is easily the most important current series in baseball. Oakland recently stunned the sport by chasing Houston down from behind to temporarily grab first place in the AL West. The Astros were back in front entering this series.

Of course, not only is this an important series in a divisional race, but the eventual runner-up likely will play the Yankees in the AL wild-card game. As it stands now, the Yankees would host that one-game showdown for the right to battle the Red Sox in a best-of-five series.

Oakland was able to catch Houston by playing at an amazing pace for several weeks. The peak period was June 16 through July 26, when the A’s went 27-7. But, they were 18-9 since then through this past weekend’s series at Minnesota, representing a 45-16 overall run entering the Minute Maid matchup.

Houston suffered through a short-term slump that helped the A’s catch up. Though, that slump was mostly just a matter of superstar second-baseman Jose Altuve missing time with an injury. He returned, and Houston started crushing opponents again.

2018 Astros records

When Altuve’s healthy, Houston is the equivalent of a 107-win team over a 162-game season. In betting terms that’s the same as -195 on a daily money line.

Having a great player at second base gives teams a massive advantage over most of the field. That’s a “defense-first” position because no lineup can afford to have a poor defender in the keystone combo. Some great defenders aren’t very good hitters.

Interestingly, Houston doesn’t have as dramatic an edge over the A’s as other teams. Take a look at “weighted runs created-plus,” which is a respected offensive analytics stat that adjusts for league and home ballpark (source: Fangraphs).

Best 2B in 2018 WRC+

Those numbers mean Altuve is creating 41 percent more runs than the average player would in his number of at-bats, Baez 36 percent more, Lowrie 27 percent more.

Baez is getting a lot of fan and media run as a potential MVP in the NL. The two best AL second basemen are squaring off again Tuesday, significant contributors to offensive juggernauts. Look for the Astros, A’s, and Cubs to continue surging down the stretch as long as their second basemen are producing at those levels. Come October, look for offensive difference-makers at the “defensive” positions.