The transition from the minors to the majors is a difficult one for all players, but sometimes pitchers can make it look easier than it really is. Noah Syndergaard comes to mind from last year. Michael Fulmer put on a really good run at the start of the season this year. However, pitchers generally experience some rough patches as they transition to the majors, and that has been more true this season than in any year in the past decade. Despite contributions from players like Fulmer, Jon Gray and Steven Matz — and debuts by more high-end talent than we have seen in two decades, including players like Lucas Giolito, Alex Reyes, Blake Snell, and Julio Urias — this year’s class of rookie starters looks to be the worst-performing class of the last decade, and this year’s increase in offense might be behind those struggles.

Back in 2012, in a class led by Yu Darvish and featuring Mike Fiers, Lance Lynn, Wade Miley, Matt Moore, and Jarrod Parker, rookie starting pitchers produced a collection 53.7 WAR, the most in major-league history. The class wasn’t just about quantity, either: the group averaged 2.2 WAR per 200 innings pitched, itself one of the higher figures in history. The 2013 class produced just 35.3 WAR, averaging 1.8 WAR/200 IP, while the 2014 class — headed by Jacob deGrom, Collin McHugh, Marcus Stroman, and Masahiro Tanaka matched the 2012 group with 2.2 WAR/200 IP, and produced 44.4 WAR in fewer innings. Last year’s group was solid in quantity, recording 40.4 WAR as a group, but only a 1.7 WAR/200 IP. This year’s class has produced just 27.4 WAR in total and 1.5 WAR per 200 innings. The graph below documents total WAR by rookie pitching classes since the 1986 season.

The 2004 season, which marked the first year of penalties for steroid testing, wasn’t a great year for rookie pitchers, and it was actually pretty poor year for rookie hitters, as well. Why? Perhaps teams wanted to see what their current players would do under the new testing rules. Perhaps mere randomness is the cause. Elsewhere on the graph, we find a low point during the 1994 strike, which is unsurprising given the relative lack of games that season. Even with 10% of the season left, 2016 isn’t going to shape up as a banner one for rookie starting pitchers. After the introduction of steroid testing, there looks to be a not-so-steady, but evident incline in the contributions of rookies.

While we could write off the decline as part of random variation given the up and down nature of the graph, this is the first time since 1999 and 2000 that rookie production from starting pitchers has declined for two straight seasons. We might also believe that we’re seeing a sort of natural correction to the increasing numbers over the past few years — as more and more young players break in and produce at a high level, that leaves less room for newer players to break in. However, we’re not just seeing a decline in quantity; the quality of the rookie starting pitchers this season is also at a pretty low point.

The graph below shows that the WAR per 200 innings pitched of the rookie starting pitching classes dating back to 1986, as well as the MLB-wide FIP and the rookie-starting-pitching FIP during that time.

The thick blue line is rookie-starting-pitcher WAR per 200 innings pitched. Not only has this year’s class fared poorly in accumulating overall WAR, it is also performed poorly on a rate basis, at 1.5 WAR/200 IP — the lowest its been since the 2008 season. The only seasons in this sample during which rookie pitchers have recorded a mark below 1.5 WAR/200 IP are 1996, 2001, 2002, and 2004. On the top two lines of the graph, MLB FIP and rookie FIP line up with each other and move in parallel over time. One thing you might notice, though, is that, over the last two seasons, FIP has moved pretty harshly upwards as the WAR/200 IP has moved in the opposite direction. As run-scoring has gone up the past few seasons, the quality of rookie starting pitching has gone down. FIP and the quality of rookie pitching don’t have a directly inverse relationship (r= -.46), but, it’s hard not to notice the FIP spikes in 1996 and 2004 that also resulted in a lower quality of rookie pitchers.

Since 2007, FIP has moved steadily downward as starting-pitching quality from rookies has improved, at least until the last two seasons. It would seem possible that, the better offenses are relative to the overall level of pitching, the harder it is for rookies to come in, be impactful and make the adjustments necessary to succeed at the major-league level. One could make the argument that the quality of rookie pitchers is down this season, but more top-20 pitching prospects have made their debut this season than at any time in the past two decades, going by Baseball America preseason top-100 lists. (The entire list of players is at the bottom of this post.)

This season has featured the debut of more top-10 prospects (Giolito, Urias, Reyes) and as many top-20 prospects (Snell, Tyler Glasnow) as the previous three seasons combined. Here are the stat lines for the five players who have made their debuts this season.

Top-20 Pitching Prospects Making Debuts in 2016 Name Team G GS IP K/9 BB/9 HR/9 BABIP ERA FIP WAR Julio Urias Dodgers 16 14 72.0 9.8 3.6 0.6 .362 3.50 3.25 1.6 Blake Snell Rays 16 16 77.0 9.6 5.3 0.6 .352 3.62 3.61 1.4 Alex Reyes Cardinals 9 2 28.0 10.9 5.1 0.3 .242 1.29 2.89 0.6 Tyler Glasnow Pirates 3 2 11.1 7.9 4.8 0.8 .324 5.56 4.64 0.0 Lucas Giolito Nationals 5 4 19.1 4.7 5.1 2.3 .281 5.59 7.33 -0.5 SOURCE: Prospects per Baseball America

The struggles of Giolito and Glasnow are evident from the stat line. Reyes has been brought up mostly in long relief, but has performed well in that role. Urias and Snell have done well, but it took some adjustments. In his first eight starts, Urias recorded a 4.95 ERA and 3.55 FIP; in his last six starts, 2.02 and 2.94, respectively. Snell has had trouble finding the strike zone and failed to make it to four innings in four of his last six starts.

We could point to the lack of opportunities for Giolito and Glasnow and the lack of opportunities for Reyes in the rotation as an argument for why the rookie stat line is down this year — and why the sheer quantity of debuts is not meaningful. We could also point to the teams choosing to limit opportunities, even for top prospects, as a recognition that, with the increased offenses, breaking into the majors is very difficult this year. There’s also the theory that the difference in the ball from the minors to the majors has an effect.

While this year doesn’t feature a Darvish-level rookie, Kenta Maeda’s 3.1 WAR equals that of Masahiro Tanaka’s rookie season in around 20 more innings. Less-hyped players like Tyler Anderson and Zach Davies are having solid seasons, while Junior Guerra is experiencing one of the best old-rookie seasons of all time. However, this rookie-starting-pitcher class, on the whole, is having a rather unproductive season, and the reason might have to do with the increase in offense causing a more difficult transition to the majors than we have seen in roughly a decade.

Here’s the list of players who made their debuts after appearing among the top 20 of Baseball America’s preseason prospect list: