J Niese recent success is due to?

ESPN TMI (Insider only, $ site), takes a look at J Niese's recent success (5-0 with a 2.43 ERA in six starts) after his return from the DL, and mainly attributes it to a low BAPIP, specifically on ground-balls. During this six start stretch, his ground-ball BAPIP is .155 during this stretch, when league average is .231, and prior to this stretch, it was .306 for his first eight starts of the year. With that data, there are three possibilities: 1) Dismiss it as pure luck. 2) See if it is a "controlled skill"/if the balls are being well-hit but right at the fielders, or 3) Believe that the defense has greatly improved with I Davis and the absence of L Castillo.

It's probably a combination of three, but here were some very interesting stats from that article.

In his first eight starts, 13.9 percent of groundballs hit into play were “well-hit” balls, which is above the league average of 12.9 percent. But in his last six starts, only 6.9 percent – a mere four of his 58 grounders in play – were “well-hit”.

Niese also appears to be benefitting from a vastly improved infield defense in his last six starts. According to Baseball Info Solutions, in his first eight starts, the infielders combined for a plus-minus rating of minus-2.4, which means that they made two fewer plays than the average infield would have made; in his last six starts, the infield was plus-6.3, as they have combined to make six plays more than the average infield.

My Take: This was very informative and highlights how much the improved defense helps a ground-ball pitcher like Niese, and the reason why I believe Tejada should still be the starting 2B when Castillo returns.