You may not have realized it — I certainly didn’t — but, Jorge Polanco has been on a tear for 30 days now. Here are the Twins shortstop’s numbers in the past 30 days, followed by his career numbers:
Past 30: 0.377/0.417/0.708, 7 HR, 4 SB, 193 wRC+, 0.402 BABIP
Career: 0.268/0.319/0.420, 14 HR, 15 SB, 93 wRC+, 0.301 BABIP
Those career numbers are over 726 PA (just over one full season’s worth). Obviously, the BABIP jumps out at you right away. In this post, I’m trying to determine if he can keep this hot streak up for the rest of the year. It’s clear that he isn’t a 193 wRC+ hitter for the rest of his career now, but can he even keep it up for three more weeks? That’s what we care about in redraft leagues, anyway. A shortstop with these numbers can win you a championship.
To figure out if he can extend this hot streak, I’m going to make liberal use of Fangraphs’ 15-game rolling average charts. Thanks, as always, to Fangraphs for the great data. Here’s the graph for his BABIP.
You can see that this recent stretch involves 15-game average BABIPs he has never had before. He’s been over 0.400 for short periods before, but never near the 0.500 mark. Also, take note that his BABIP has been falling in the past 10 games or so, returning back to league average. So far, it looks like he is already coming back to earth and not a good bet to keep it up.
Not only has his BABIP been high, but his power has soared as well. Half of his career home runs came in just 30 days. Let’s see if his hard-hit% backs up this power surge and if he’s ever shown it before.
Early in the year, he had a stretch with an even better Hard% than recently. So, his recent increase is certainly not unprecedented for him. Also, his increase in hard contact does seem to coincide with his power increase, but what is interesting is that his BABIP does not seem to correlate with hard hit %. Early in 2017, he was hitting the ball harder than ever before, but his BABIP was below average. Maybe part of the power boost was due to HR/FB% and not just hitting the ball harder.
There it is. His HR/FB% shoots up to well above what it ever was before, coinciding with his power increase.
I just thought I would show this graph to hammer home the point. When a disproportionate number of his fly balls started to make it over the fence, his number of home runs shot up faster than ever before. Now, it could also be true that he is hitting more fly balls than ever before as well.
Sure enough, it’s true! He has always hit a pretty large number of fly balls, but he’s been over 50% recently. I’ll save you a graph and just say that he hasn’t been pulling the ball any more than usual lately, so these fly balls are to all fields.
Ok, so we know his BABIP is unsustainable, his HR/FB% is unsustainable, and he’s hitting a ton of fly balls to all fields. The last question is: how much authority is he putting into his fly balls?
I graphed his exit velocity on fly balls and line drives thanks to Baseball Savant and calculated the rolling average exit velocity.
It looks like this is the final nail in the coffin for Polanco. His exit velocity hasn’t really increased, he’s just been getting lucky with more fly balls leaving the park. His exit velocity on flies and liners has hovered around 90 mph for most of the season. It hasn’t surged much recently. That puts him in the bottom half of MLB hitters. I just don’t see a real change in power here.
So, the answer to my initial question is no, you cannot count on Polanco down the stretch of the fantasy season. He has already started to regress. His hot month was just that and nothing more. He got lucky and his luck is running out already. If you were counting on him to fill your SS spot the rest of the year, you might need to look elsewhere. Tschus!