What Does It Mean To Be a September Power Surger?

There are many narratives out there when it comes to how to evaluate September offensive statistics. From a fantasy angle, we're always trying to view the most recent data to see if there are trends, since identifying trends is where we can get the most bang for our buck on draft day. You have one school of thought which says that September stats are meaningless - and if you read or follow Keith Law on Twitter, you know he belongs to this camp. Then you have the other side of the coin who thinks you can identify breakout players by viewing them within the context of the previous season's stretch run. Maybe they are players who made mechanical changes. Maybe they are players who finally got an opportunity to play every day. The question remains: how much should we draw from September performances?

Because of Jose Bautista, we now look at some of these players a little more closely - whether it's fair or not. Sure, Bautista's 10 September HR in 2009 was a signal of things to come with him, but Brent Morel hit 8 HR in September of 2011 and we're not exactly debating between him and Adrian Beltre.

The argument that September statistics are inflated due to roster expansion is often cited, but is a hitter really more likely to hit well in September? The league as a whole has a .725 OPS for the 2012 season. In September, the league actually had a .722 OPS - not quite what you expected to see, right? And while HR are elevated in September, the difference is slight - 17.1% of 2012 HR were hit in September, just slightly more than the 16.7% you'd anticipate. That's an extra 23 HR league-wide. And if you expand that out to the last ten years, you end up at 17.3%, which still works out to just over 1 HR per team per September.

For today's post, we're going to look at some of the players who had a great month of September in the power department and how we should view the fact that they had a great month of September. First, for fun (and without additional context), your Top-10 September fantasy hitters according to the ESPN Player Rater:

Chase Headley, Ryan Braun, B.J. Upton, Jimmy Rollins, Miguel Cabrera, Bryce Harper, Adrian Beltre, Ichiro Suzuki, Norichika Aoki, Ian Desmond

Not exactly a replication of your 2012 ratings - only four of those hitters (Headley, Braun, Cabrera, Beltre) are in the Top-20 for the season. In fact, Harper, Ichiro and Aoki all fall outside the Top-50 hitters in 2012. It's certainly interesting to see, but we're here to talk about power. And for the purposes of this exercise, we're going to take a closer look at power output from two different perspectives (HR and ISO) between 2010 and 2012 and how they carried over from the previous September. Chronologically we will go, so let's start with the year of Jose Bautista's end-of-season breakout, 2009:

The yellow highlights are players who set a career high in HR the following season. Even including the stars on this list, only three 30 HR seasons came from guys who exploded during the previous September. One particularly interesting name on this list is Andres Torres, whose 2010 season (16 HR, 26 SB) was by far the best of his career - though unfortunately the power only lasted for one year. And yes, Randy Ruiz led all of baseball in Isolated Power during September of 2009. Baseball is awesome.

Moving forward, here's 2010:

The asterisks are players who were on the leaderboard during their rookie season. So while Stanton did set a career high in HR during 2011, it was also his first full season. The big name you'll notice here is Curtis Granderson - who hinted at his 40 HR power in the twilight of the 2010 season. You can also see that Edwin Encarnacion, 2012's breakout power hitter, is on here - though he doesn't count as a success story for these purposes because of the extra year in between.

And finally, here is 2011:

It may be coincidental that Ryan Braun and Miguel Cabrera both set career highs in HR after having very strong Septembers. They were both clearly studs before this (and were likely two of the top four picks in your draft). Again, the interesting name here from a positive perspective is Allen Craig. The only reason he's not on the chart to the left is that he only got 52 AB in September of 2011. And, yes, the Brent Morel and Shelley Duncan Septembers really happened.

So far in each of the last three seasons, we've found one player which was a September surger with predictive value (Bautista in 2009, Granderson in 2010 and Craig in 2011). Which brings us to the September which just ended. The only thing left to answer is whether any of these September surgers will continue their performance into 2013:

Starting at the top, the elder Upton is an interesting name to see here on a couple of levels. First of all, he's never hit 30 HR in a season (unless he hits two more this year). Second of all, he's a player who had plus power potential coming up through the minor leagues. Third of all, throughout his entire career, Upton's power numbers have historically spiked in September (his 31 career September HR are more than any other month). Here is his AB/HR rate by month for his career (27.7, 42.5, 32.9, 36.9, 29.0, 22.4). And finally, he's a free agent who could conceivably end up in a hitters' park after playing his entire career so far in Tampa Bay. But finishing just shy of a 30-30 season, Upton is unlikely to be undervalued.

Chase Headley has been talked about a lot, including this post by Ray from two weeks ago. Could Chris Davis be that guy? Sure, he does have 31 HR on the season in 2012, but in September he's looked more like the hitter he was in April and May (both in power and reducing his strikeouts). But if there's going to be one guy from this list that outperforms his power expecations in 2013, I know who I have my eye on.

We know that Bryce Harper is one of the most hyped prospects in the history of the game. We also know that he's the first teenager to hit 20 HR in the majors since Tony Conigliaro in 1964 (they are the only two players to accomplish that feat in MLB history). Ray also wrote a recent piece on Bryce Harper here, suggesting that he could be a Top 15 OF next year (potential going 25-25). I actually think Ray is a little light on Harper's 2013 upside - he could hit 35 HR and I wouldn't be surprised in the least.

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