2019 MLB Draft Preview: Mining for Diamonds

If you were trying to find the next ballplayer with a career worth of 10+ WAR, and you had to pay a $4 million bonus to sign them, who would you pick: the 21-year old college player or the 18-year old high schooler?

It’s a tough choice because you can find success stories with either route. The process is arduous, and like mining for diamonds, it requires sifting through tons of low worth rock hoping to find that dazzling gem. Teams have invested in scouts and new technologies to roam baseball fields across the country to find players worthy of that multi-million dollar investment.

From 2005 to 2014, 501 players were selected in the first round with 343 making the majors at a success rate of 68 percent. Of those that do make the majors, first rounders have an average career of 6.2 bWAR. These numbers seem low for how much importance is placed on the draft in team building.

Then you compare them to the previous decade. From 1995 to 2004, 414 players were selected in the first round, and only 63.7 percent made the majors. However, these players were on average better with a career bWAR of 9.2. More players are making the majors from the first round, but not at the same quality level as a decade before.

Regarding “Diamonds,” or players who are valued at 10+ bWAR for their career, we’ve only seen 152 players drafted to meet that mark from 1995 to 2014. That’s a whopping 16.6 percent rate of developing a player who over five years would be considered an average major leaguer.

It’s safe to say that the MLB draft has been a challenge to teams.

Breaking it down further college players have a much higher success rate of reaching the majors compared to those drafted out of high school. 

Only in 2002 and 2004 did prep players make the majors at a higher clip than their college counterparts. From the 2014 draft, only 25 percent of prep players selected have reached the majors so we should see that number increase after the 2019 season. One would think that the majority of first-rounders would be college players to at least ensure good odds that the multi-million dollar investment gets seen in the majors. That hasn’t always been the case. Last year, more prep players (23) were selected than college (20), and we’ve seen stretches of this trend from 1995 to 2000, and 2010 to 2012.

When drafts have gone prep heavy in the first round, only the 1995 class saw a success rate of more than 60 percent of players reach the majors. Funnily enough, it’s when drafts that are very heavy on college players selected in the first round we see terrific rates of prep players reaching the majors.

If Step One in having a successful first round pick is reach the majors, teams should be selecting college players. From 2003 to 2014, 78.9 percent of college players picked in the first round have reached the majors. Already 55 percent of college players selected in 2015 have reached, and we’ve seen a couple from the 2016 and 2017 classes make their debuts. It’s a clear indication that teams are doing a much better job of scouting players at the collegiate level, and that additional experience is helping these players adjust to minor league baseball better.

However, just because college players are making the majors more frequently, are they producing at a higher level than their high school counterparts?

Of the 152 players since 1995 drafted in the first round with a career of 10 bWAR or higher, 87 of them have been college players, or 57.2 percent. 68 drafted prep players have reached a career 10+ bWAR, and just three junior college players have reached that mark.

Based on historical data, yes, college players have been producing at a higher level.

Will that trend continue? Looking at the 2019 Top 100 Prospect list breakdown, prep players almost double the number of college players listed.

Today, teams mining for the best possible outcome from the draft are better off to invest the millions on college players in the first round, but it might be a different story soon. Thanks to TrackMan, scouts can compare spin rates for pitchers, and exit velocities for hitters, to current minor and major leaguers. More showcases continue to pop up that pit the top tier prep players against one another.

There are more data points and film on prep players than ever before, and that will only help scouting departments make better-informed decisions in the draft room. These efforts should assist in closing the gap in production between college and prep players. Looking at the next wave of talent to wash ashore in the majors, and another impressive prep class available for the 2019 Draft, maybe a new trend is about to start.

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There’s usually a consensus top 3-5 draft eligible players. For this draft, I’m far more concerned about their ability to develop that pick.


Josh, can you calculate the percentage of college players in the first who get to 10 WAR vs. prep?


Good article, and the following critique doesn’t invalidate the main focus/conclusion of the article about whether diamonds are better found via college players or prep players, but isn’t part of the analysis early in the article flawed? You compare average career bWAR between players drafted from 1995 and 2004 and those drafted between 2005 and 2014 and conclude the players drafted between 1995 and 2004 were of a higher quality. However, the first set of data is mostly complete – almost all of the players in that first set have accumulated all of their bWAR. There are many players still active in the second set of data, and they will accumulate much more bWAR in the coming years. It seems to me that you’d have to wait until about 2030 to make an accurate conclusion using average career bWAR between the two sets of draft picks, allowing time for most of the players from the second set to be done with their careers.