Danny Valencia is swinging for the fences

Danny Valencia, the Oakland Athletics' recent third base addition, had a strong night at the plate on Friday. Going 3-for-3 with a walk and two home runs, he hit the game-winning bomb in the 8th and was the largest contributor in the team's victory over the Astros.

Valencia was plucked from the Toronto Blue Jays on the August waiver wire after their hectic trade deadline resulted in a roster crunch. This is despite having what has been a stellar offensive season. With the A's, that performance has continued.

Sporting a 133 wRC+ and .237 ISO, he has managed to slug 16 home runs without being given full-time plate appearances. It appears that this newfound success is being driven by a more aggressive approach.

He maintains strikeout and walk rates that hover at and below league-average levels, respectively, but in 2015 he is swinging at a higher rate than at any other point in his career. Valencia's 36.0 percent chase rate is up from his 29.7 percent career rate, while his 62.1 percent swing rate in the zone is also up from his 58.3 percent career rate (data per Fangraphs).

He is making slightly more contact outside the zone and overall isn't striking out more frequently than in the past. The net negative of this swing-heavy approach is his higher ground ball rate, which has jumped to 51.3 percent after having a cumulative 43.9 percent rate from 2010-2014. By swinging more at everything, he's also swinging more at breaking pitches, a career weakness, and potentially generating weak contact on more balls that he is chasing. Fortunately, being right-handed limits his susceptibility to shifts.

Obviously, the sum total of Valencia's performance has more than compensated for the ground ball issue, because he's hitting fastballs and hanging breaking pitches over the plate really, really well. Per Baseball Savant, he actually ranks third in average exit velocity (93.6 MPH) among all major league hitters with at least 100 balled balls. He's hitting with power to all fields as well, with a .324 pull-hit ISO and a .318 ISO to the opposite-field (data per Fangraphs).

Some of this rediscovered power may come from a mechanical adjustment, as he appears to be employing a more pronounced leg kick in many appearances this season.

Here are four examples on home runs hit by Valencia in 2015.

Compare those against all four of Valencia's home runs hit in 2014, which feature the double toe-tap.

He seems to be intent on driving the ball, and it is clearly working. This combination of aggressive approach and demonstrable power has led to pitchers adjusting by throwing fewer fastballs to Valencia as the year has progressed.

Fortunately for him, this has corresponded to higher walk rates and fairly steady production (data per Brooks Baseball and Fangraphs). In addition to throwing fewer hard pitches, opposing pitchers are attempting not to throw the ball in the upper-third of the zone, where he's done most of his damage.

In previous years (2010-2014), pitchers may not have been very intimidated by Valencia and threw all over the zone. In 2015, they are clearly targeting pitches down and away with more frequency.

This trend is a potential cause for concern unless he can adapt to lay off a few more of those low pitches. If Valencia maintains the same aggressive approach, he'll probably still run into a lot of mistake high fastballs or hanging sliders, but with less total value. There's a reason that not a lot of hitters hit that many ground balls while still hitting for power.

Were the season to end today, Danny Valencia would be in uncommon territory with regard to his ground ball/power combination. Dating back to 2002, the first season for which Fangraphs reports batted ball data, there are only 14 individual seasons with a ground ball rate above 50 percent while still having a .200 ISO or higher. That's with a fairly lenient 300 plate appearance minimum.

A couple things are noticeable about this list. First, four out of the 14 seasons are currently happening in 2015. There are still a few weeks of games left to change that, so that's something to be looked at at the conclusion of the season. The second noticeable feature of this list is that, aside from Jacque Jones in 2002 and 2006, players aren't doing this kind of thing numerous times.

It is a very small sample of batters, but that's for a reason - it is an uncommon occurrence, and it doesn't appear to be sustainable. In almost all of the cases above, the regression the following season came more at the expense of the power than the grounders.

This should not be seen as evidence that Valencia is 'doomed' or anything of that sort - almost all of the above seasons were followed by one or more above-average offensive years. There's merely a strong chance that he won't continue to produce plus-plus power in the future unless his eye improves.

For the time being, Danny Valencia has adapted a more aggressive approach and is driving the ball further with great success. He has holes, and pitchers are beginning to adapt to him. He'll have to demonstrate that he can make a change right back at them.

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Spencer Bingol is a Contributor at Beyond the Box Score. You can follow him on Twitter at @SpencerBingol.