For those that watch baseball religiously, a lot has been made of the so-called five tools that scouts look to when evaluating players. While fielding and throwing are important, they typically don’t matter to fantasy players. Most fantasy players focus on the other three tools: hitting, hitting for power, and speed. That translates into hitting for average, hitting for power, and stealing bases.

More and more leagues are including an on base element. That could be walks or on base percentage. Even leagues that continue to use the standard five categories can take advantage of what some lovingly call the sixth tool (or fourth fantasy tool): plate discipline. As scouts and baseball executives are becoming increasingly aware, players are born with plate discipline or are not.

Essentially, the difference between the hit tool and the plate discipline tool is that with the plate discipline tool you are able to recognize which pitches you should swing at. When looking at the data, the key statistic (as found at Fangraphs) is Oswing. That is the percentage of pitches outside the strike zone that a hitter swings at. Talented hitters can make contact on those pitches, but usually it is the kind of contact pitchers want.

Plate discipline is only one of the four tools that fantasy players look for, so you shouldn’t govern your entire draft based on plate discipline, but it does allow us to find the occasional sleeper and avoid the occasional bust. In this series, we will identify a couple of sleepers and a couple of players who could end up being busts.

Sleepers

Francisco Cervelli

Cervelli played full time for the first time last year and that could be seen in the Oswing numbers. Experience tends to improve those numbers some, but even when he was playing part-time, he still was better than the league average in that department. Even though Cervelli doesn’t have a tremendous hit tool, he still makes more contact than the average player because he doesn’t swing at pitches out of the strike zone. Add a decent walk rate with an above average contact rate and you get a good batting average and good on base percentage.

Yasmani Grandal

Like Cervelli, Grandal doesn’t necessarily have a well developed hit tool. Even with his advanced plate discipline, he still is slightly below average on his overall contact rate. These numbers don’t show the power and that is one of the advantages you get with Grandal. So, despite his career .241 batting average, he offers on base percentages well above the league average. He is a huge sleeper in six category leagues.

Rotters

Salvador Perez

Some prognosticators like to use the label “bust.” The rotter label is really more apt for most of these guys. You can see the decay before your very eyes. His strikeout rate is increasing and the walk rate is decreasing (although it really has nowhere else to go). Pitchers are figuring out that Perez will fish for just about anything and they are taking advantage. He is still talented enough to make contact more often than not, but even that is beginning to decay, too.

Yan Gomes

Imagine that 2015 was a down season for Gomes and his contact rates actually looked pretty good. However, like Perez the oswing rate continues to rise and with that comes the greater odds that both will become so-called fantasy busts. We shouldn’t call them that because we can see the regression, but some will still fall prey to it. Unlike some other guys, this one won’t exactly come out of nowhere.