Mike Trout's baserunning: OK, so pretty much everything Mike Trout is doing these days is noteworthy. But from the subtle factors, here's a nice one: Trout is not only stealing bases, he's not getting caught.
Trout has 33 steals through the Angels' first 106 games. He wasn't promoted until Los Angeles' 21st game, so depending on how you run the numbers, he's either on pace for 48 or 52 steals on the year. The fairer way to Trout gets you 52. Either way, if he stays on both paces, it's historic.
Since 1980, exactly four players have stolen at least 45 bases with a success rate as high as Trout has right now: Ichiro Suzuki, Jimmy Rollins, Davey Lopes and Jerry Mumphrey. Only one, Mumphrey, stole 50 or more with that high a success rate. In fact, there are only four players in that time frame with at least 50 steals and even a 90 percent success rate.
The Pirates, the Reds and inherited runners: By most measures, the top two teams in the National League Central have two of the best bullpens in the Majors. The Reds and Pirates rank 1-2 in baseball in relief ERA. Pittsburgh is first and Cincinnati eighth in save percentage. Reds relievers have allowed the fewest homers, Pirates relievers tied for ninth-fewest.
It's one big reason why the team with the best run differential in all of baseball, St. Louis, is in third place in the division. The Cards haven't been as good finishing off wins as the two teams ahead of them.
Here's an underlying factor: the Reds and Pirates are also the two best teams at preventing inherited runners from scoring. Pittsburgh ranks first, at 18.4 percent, with Cincinnati second at 18.5 percent. That's less predictive than something like strikeout or walk rate, but it's a very good explanation as to why both teams have had success this year.
One difference between the two, by the way: Reds relievers have thrown the fifth-fewest innings of any bullpen in baseball. The Pirates have the 13th-most. It's not a huge gap, 26 innings, but every little bit matters when you get to September.
The air in Oakland: Oakland Coliseum is always a pretty good place to pitch, but it's been especially forgiving this year. You'd better hit a line drive, and place it well, if you want to do damage against the A's pitchers in their house.
The A's sport the fourth-best home ERA in Major League baseball, and the best in the American League, at 2.92. That's as compared to a 4.07 ERA on the road. And yet it has very little to do with two of the key factors in run prevention, strikeouts and walks. Athletics pitchers have very similar walk and strikeout rates at home as compared to on the road. So it doesn't seem as though it's a matter of the hitting backdrop or vision-related issues.
No, it's a matter of what happens once the ball is hit. A's pitchers have allowed a .253 batting average on balls in play at home, compared to .302 on the road. Only 7.2 percent of the fly balls hit against A's pitchers at home have gone for home runs, the lowest ratio in baseball, as opposed to 10.0 percent in road games.
Starlin Castro in the daylight: Starlin Castro's numbers are down a bit this year, leading a few folks to forget that we're still talking about a 22-year-old shortstop who already has 465 big league base hits. There's something strange about it, though: his performance has been particularly rough in day games.
Not at Wrigley Field, specifically, but in day games anywhere. Castro has very little home-road split this year. He has a very big day-night split. In night games, he's hitting about like he did a year ago: a .304 average, .327 on-base percentage and a .464 slugging percentage. In day games, his line is .265/.295/.403. He's actually struck out more often at night, and walked about the same amount.
Don't throw Andrew McCutchen a fastball: Nobody's done more damage, in general, than Andrew McCutchen this year. Let's get that out of the way up front. He is batting .373 and leading the National League in slugging. But more specifically, nobody's done more damage against fastballs than McCutchen, and it's not close.
According to FanGraphs.com, McCutchen has produced 3.98 runs above average per 100 fastballs he's seen. Second place is David Ortiz, at 2.98. For some perspective, the gap between McCutchen and Ortiz is greater than the gap between Ortiz and 14th-place Paul Konerko. McCutchen has been effective against every kind of pitch this year -- his wFB/C (that's how it's notated, in case you're interested) is positive against every pitch type but the knuckleball. But his effectiveness against the fastball is absolutely unparalleled.
Matthew Leach is a writer for MLB.com. Read his blog, Obviously, You're Not a Golfer and follow him on Twitter at @MatthewHLeach. This story was not subject to the approval of Major League Baseball or its clubs.