Browsing around on Twitter yesterday, I saw someone mention that Vladimir Guerrero Jr. has walked as much as he’s struck out so far this season (17 BB to 17 K, not counting the 5 intentional walks he’s received). This is obviously an incredible feat, but it is even more incredible considering that Vladito is doing it as a 19-year old at AA ball. A hitter who walks as much as he strikes out shows us a few things. It obviously shows us a hitter who is seeing the ball well. Also, it shows that the hitter has a great understanding of his plate coverage and the strike zone. Finally, it shows that the hitter is not being fooled by the offspeed pitches he’s seeing. Basically, it confirms that a certain hitter is displaying an advanced plate approach for his given level.

I am also a fan of looking at a hitter’s ‘isolated power’ (ISO) percentage. ISO is a metric to measure a hitter’s power by looking at how many extra bases a hitter averages per each at bat. The idea has been around a long time, as it was a brainchild of Branch Rickey. Mechanically, you take a hitter’s slugging average (TB/AB) and remove his batting average (H/AB). I like to look for hitters with an ISO above .200 as a great indicator of future power potential. Vladito’s ISO is currently a nice .269.

The final thing we are going to look at is the hitter’s ‘green bean ratio‘. The green bean ratio takes a hitter’s groundball rate and compares it to his line drive and flyball rates. The formula is GB/(LD+FB). A green bean ratio of 1.0 means a player is hitting the ball in the air as much as he’s hitting it on the ground. A ratio of 0.5 means he’s hitting it in the air twice as much as he’s hitting it on the ground. The green bean ratio can help identify a player who has changed his swing approach to generate more balls hit in the air, and should therefore add more extra-base hits. For example, Vlad Jr.’s ‘green bean’ in 2017 was 0.945. This year, he’s hitting a few more line-drives and a lot more flyballs, bringing his green bean up to 0.651. In other words, a change in Vladdy’s approach or a maturation in his power hitting has led to more line drives, flyballs, extra-base hits, and home runs.

Now that we have built a hitting profile off of Vladito (BB>K, ISO > .200, Dropping Green Bean Ratio), let’s look at the MiLB hitters who qualify:

Player Name Class At-Bats ISO Walks Strikeouts AVG OBP SLG Green Bean Bradley Policelli A-Full 54 .204 11 10 .241 .388 .444 .869 Yusniel Diaz AA 78 .205 15 13 .308 .419 .513 .422 Josh Rojas AA 68 .206 10 9 .397 .468 .603 .679 Cullen Large A-Full 63 .206 13 10 .286 .425 .492 .656 Yadiel Hernandez AA 108 .222 20 18 .315 .426 .537 1.5 Corban Joseph AA 147 .224 14 9 .327 .380 .551 .642 N oel Cuevas AAA 63 .238 10 9 .333 .419 .571 .892 T yler White AAA 155 .245 30 21 .355 .471 .600 .357 D avid Fletcher AAA 173 .249 12 10 .364 .410 .613 .883 A len Hanson AAA 62 .258 8 7 .403 .479 .661 .800 V ladimir Guerrero Jr. AA 152 .276 16 15 .421 .472 .697 .651 K acy Clemens A-Full 93 .323 25 22 .301 .454 .624 .1.061 D aniel Vogelbach AAA 83 .410 22 10 .301 .449 .711 .520 J uan Soto A-Adv 62 .419 11 8 .371 .466 .790 .782 J uan Soto A-Full 59 .441 14 13 .373 .486 .814 .782 M ac Williamson AAA 50 .560 8 7 .440 .548 1.000 1.277

Statistics as of 5/23/18

Let’s start unpacking.

First, the two hottest hitting prospects of 2018, Vladimir Guerrero Jr. and Juan Soto, both appear on the list. We described Vlad’s profile in the introduction. He’s changed his already solid approach to include more line-drives and flyballs, and he’s consequently hitting for more power.

Juan Soto is on here twice, as his profile at both A-Full Season and A-Advanced ball hit our criteria. Anyone who was watching the guy at the lower levels of the minor leagues this season noted that, like Vlad, Soto was just head-and-shoulders above the rest of the competition at each level. What’s also interesting about Soto’s profile is that he had the exact same green bean ratio at both A-ball stops (.782). He’s a 19 year-old with advanced plate control. I would not be surprised to see him continue his success at the MLB level.

Yusniel Diaz is a very interesting name on this list. Diaz, at age 21, is a little young for his AA level. Diaz ended 2017 at AA, and the Dodgers chose to start him at AA again this season. He is obviously tearing up the competition in his second look at AA ball. But what’s also interesting is that Diaz adjusted his swing last year in an effort to pull and elevate the ball more while hitting. This is reflected in his extreme green bean ratio of .422. He’s really elevating the ball. Diaz should be on the radar for a promotion to AAA soon, as he’s looking like he’s simply too advanced for his level. However, don’t look for much additional power hitting from him, as he’s already pushed his green bean ratio about as low as it can go.

David Fletcher, a 23-year-old middle infielder, finished last season with the Salt Lake Bees, the Angels AAA affiliate. The Angels started him back at AAA again this season, and everything about his approach there in 2018 suggests that he’s too advanced for the level. He’s been incredibly hard to strikeout this season, whiffing in only 6.7% of his plate appearances. He’s also now hitting for some significant power, posting a .243 ISO. Like Diaz, Fletcher recently noted that he’s made some adjustments to his swing, including changing his bat plane. A great contact bat who is developing power, Fletcher should be on everyone’s radar at this point.

Daniel Vogelbach, 25, has been called up again to the Mariners. I would bet strongly on him sticking in the MLB this time around. Vogelbach has demonstrated that continuing to get AAA at-bats is going to do nothing for his development. His performance at AAA in 2018 has been extremely impressive.

Mac Williamson, 27, is another guy who, you guessed it, made changes to his swing in the offseason. Williamson hooked up with private hitting instructor Doug Latta, the same guy who helped Justin Turner turn a rebuilt swing into a late-career breakout. The changes have obviously worked for Mac at AAA (.444/.545/.963). When he recovers from the concussion he is dealing with, we will see if the approach will continue to work for him at the MLB level.

Alen Hanson, 25, has looked like a AAAA guy thus far in his career, but he is also at an age where he could still break out. He spent time with the White Sox and Pirates in 2017, but the Giants gave him a shot at a utility-role in 2018 which has worked out for him thus far. He’s posted a .409 wOBA and 167 wRC+ in 14 games this season. Want to guess why? His batted ball profile has changed significantly, with his groundballs dropping 5%, giving him a green bean ratio of .800 this season.

A lot of the other players on this list are too old for the competition they are playing against. Brady Policelli is a catcher who is a little old for his level (22 at A-Full Season). Josh Rojas is a second baseman who is a little old for AA (almost 24 years old). Cullen Large (70-grade name) is a switch-hitting second baseman who is too old for his level (22 at A-Full Season). Yadiel Hernadez was a 30-year-old playing AA ball for some reason. Corban Joseph was 29 at AA. Noel Cuevas, 26, has subsequently been called up to the Rockies, where he’s not hitting for power at all. Tyler White is a 27 year-old who is tearing apart AAA-ball. White hit for power while appearing in 22 games for the Astros last season (.246 ISO). Kacy Clemens was 23 years old at A-Full Season before being promoted by the Blue Jays to A-Full season. They should all be monitored to see if their approach remains intact upon promotion to their new level.

What have we learned? First, an advanced plate approach combined with a strong ISO can help us identify hitters who are just too advanced for their level. When those hitters are also young for their level (Vladimir Guerrero Jr., Juan Soto, Yusniel Diaz, David Fletcher), dynasty league prospectors should get excited. Second, when a hitter makes a change in his swing, watch for the results. If his green bean ratio drops and his plate control improves, his power numbers can make a big jump (Yusniel Diaz, Mac Williamson, Alen Hanson). Third, there are some hitters who have conquered minor league pitching but might need to struggle through some time in the majors to get it to click there (Daniel Vogelbach, Tyler White). There are lots of succesful hitting profiles out there. We are here to help you dig into the data and find them.