Year of the rookie

Every season is a great season of baseball. It’€™s fair to say, however, that some seasons might be better than others. If unexpected teams succeed, records are broken and exciting rookies debut on the biggest stage, we can witness something that transcends the customary ebb and flow of the regular season. At the All-Star break, the 2015 season has done exactly that.

The Twins are in the playoff hunt. A-Rod reached 3,000 hits. And, despite those unexpected and landmark events, this season’€™s greatest surprise might be the group of up-and-coming superstars who have broken into the big leagues. With Miguel Sano getting the call to the Twins two weeks ago, we’€™re now seeing many of the big-name prospects that we’€™ve been hearing about for the past few years: Kris Bryant, Joc Pederson, Carlos Correa and Addison Russell (just to name a few) are all in major-league starting lineups on a daily basis.

All of these players were at one time in Baseball America’€™s top 10 prospects list; each at one point has topped his respective team’€™s individual list. It’€™s unusual to see so many top prospects called up in the first half of the same season, and it warrants our attention. With a chance to pause and look back on the season thus far, how have 2015’€™s rookies measured up against the rookie classes of the past decade?

First, we’€™ll look at the overall pre-All Star break production of this season’€™s positional rookie class compared to those of the past decade. As a cutoff, we’€™ll look at the combined production of the top 20 rookies for each season; that will seek to isolate only the best rookies in each season. Let’€™s look at the first-half production of each rookie class by Wins Above Replacement since 2005. Is 2015 actually a great year for rookie production, compared to the past decade?

Overall_Rookie_WAR

By combined WAR, the first half of 2015’€™s top 20 positional rookies outpaces any other season in the past decade. The value of this year’€™s rookies isn’€™t just related to their names or hype; their performance has spoken for itself. Bryant and Pederson lead this season’s rookies with 3.4 and 3.2 Wins Above Replacement, respectively, which is the first time in at least 10 years that two rookies have each posted at least 3.0 WAR in the first half of a season. Only three other rookies have posted 3.0+ WAR in the first half of a season during the past decade: Evan Longoria (2008), Mike Trout (2012) and Billy Hamilton (2014).

However, given that this overall method of measurement might be biased by a few great first-half performances (the outlier players above are a good example of players influencing their respective year’s overall WAR total), let’€™s look at it another way. What we really want to see is how many rookies have performed at a high level. Let’s ask this next: How many rookies had at least 1.0 WAR in the first half of each of our sample seasons? Let’€™s take a look:

Seasons_Rookie_WAR

The 2015 season is far above all other seasons in the past decade for the number of productive rookie position players, with 17 positional rookies posting at least 1.0+ Wins Above Replacement before the All-Star break. With names like Billy Burns, Addison Russell and Jake Lamb at the bottom of this season’s list, we can tell just how strong this class of rookies has been through the first half of the season. It is, in the past decade, unrivaled in terms of depth and production.

Now that we’ve looked at the position players, let’s move on to the pitchers. Though we’ve heard about a number of high-profile rookie pitchers this season — almost half of the Mets’ starting staff, for example — the hype surrounding the rookie class of pitchers this year is not quite at the level it was for the position players. Does their production support this? First, let’s take a look at our first set of parameters, except this time with pitchers: overall Wins Above Replacement for the top 20 rookie pitchers for the first half of each season, dating back to 2005. Take a look:

Overall_Rookie_Pitcher_WAR

For rookie pitchers, this season hasn’t been anything too special; it’s about in line with the average rookie pitcher output for each of the past 10 seasons. Noah Syndergaard, Trevor May, Lance McCullers and Chris Heston lead the pack of this year’s rookies, but we haven’t quite seen the ascension of top-of-the-line prospects in the pitching department like we have with position players. That is confirmed in our next group — the number of rookie pitchers with at least 1.0 WAR in the first half of the season:

Seasons_Pitcher_Rookie_WAR

The 2015 season has been an improvement over 2013 and 2014 in terms of the number of highly-productive rookie pitchers, but it lags behind years such as 2012, which saw names like Lance Lynn, Yu Darvish and Drew Smyly debut in the majors. Though international free-agent signings might influence these numbers slightly, the fact remains: Rookie pitchers haven’t had an outsized role so far in the 2015 season when compared to the past decade, and when compared to the positional rookies.

If it seems like this season has had a lot of great rookies and blue chip prospects making their debuts, you’re not mistaken. By first-half production, this crop of positional rookies has been the best in over a decade. We’re witnessing something special this season: numerous seemingly franchise-quality players coming up around the same time and living up to their billing. Many of the positional rookies we’ve highlighted could be in the discussion for one of the best first-half rookie in the past 10 years. Most seasons, we would be fortunate to have one such rookie; this year, there are a handful of them, and that is an incredible occurrence for fans of baseball.

At the end of the season, the Twins might not make the playoffs. A-Rod’s 3,000th hit will just be a memory. But these amazing rookies we’re seeing? They’re probably just getting started.