Pete Alonso celebrating a home run with the New York Mets.

The Great Rookie Debate

Over the past couple of weeks, the debate over who should be the National League Rookie of the Year has intensified. At least it has among San Diego Padres and New York Mets fans. The national beat hasn’t picked up on this debate all that much. If anything they are framing the race as already well in Pete Alonso’s hands. Outside of a few Keith Law tweets, I have yet to read a national writer place Fernando Tatís Jr. in the same category as the Mets slugging first baseman. I’ll tell you this much right off the bat, at the end of the day I don’t think there’s much of a debate. But, thankfully we have statistics and the ability to interpret those statistics to get to a more honest assessment.

As far as bread and butter or more traditional stats go both men are fairly even. Tatís has a slash line of .327/.393/.620 with 14 home runs, 20 walks, 67 strikeouts, and 13 stolen bases to 3 times caught stealing. Alonso sports a slash of .280/.372/.634 with 30 home runs, 37 walks, 92 strikeouts, and 1 stolen base to 0 times caught stealing. Tatís is hitting for more average and getting on base more, but Alonso just edges him out in slugging. Alonso is striking out less, 24.5% to 28.6%, and walking more, 9.8% to 8.5%.  Stolen bases are a clear win for Tatís, as his 81% success rate in 16 tries is better than Alonso’s 100% in one try. Oh, and even though I think RBI are useless, a lot of NL RotY voters do not, and Alonso is crushing Tatís in that category, 68 to 33.

Those numbers paint the beginning of a picture but we need to dig a little deeper to suss out who has been better thus far this season. In terms of raw power, Alonso takes the day without question. His ISO of .354 blows away Tatís’ .293. BABIP heavily favors Tatís in terms of the actual number, .419 to .292. But, that means that Alonso has been somewhat unlucky while Tatís has had a fair amount of luck involved when he makes contact. Except, I’m not sure he really has. Yes, I know what the BABIP says, but I also know that Tatís is someone who I’d throw an 80 on when it comes to instincts, hustle, etc. That’s not a knock on Alonso, but watching Tatís I don’t think we are watching a lucky hitter, but rather someone who uses his natural ability, instincts, and smarts to hit the ball where they ain’t and beat out plays others can’t beat out.

As far as Statcast is concerned, both are having great years. Alonso’s Barrel% of 17.9 is in the top 2% of the league as is his wOBA of .416. His xwOBA of .394 and xSLG of .552 aren’t that far behind in the top 5% of the league. Meanwhile, Tatís finds himself with a top 2% wOBA of .421 and a Sprint Speed that is in the 90th percentile. These stats give a very slight edge to Alonso, but Tatís remains in the mix.

There’s more to offense than just hitting the ball or mashing home runs. Both players can do those things, but when it comes to engineering runs on the basepaths Tatís is on another level. I’ve already mentioned his Sprint Speed, his Spd of 8.4 is well above Alonso’s 3.4, and good enough for third overall in Major League Baseball. BRR gives a better indicator of overall skill on the basepaths, and again, Tatís leaves Alonso in the dust with a 7.7 to 0.4. No matter how you slice it, Alonso pales next to Tatís in speed and baserunning ability.

None of the major sites agree on who has contributed the most offensively. Most of that is due to the way the stats are set up, predictive versus representative, and what they value. Either way, WRC+ gives a very slight edge to Tatís, 162 to 161. OPS+ has both players dead even at 166. DRC+ is heavily in favor of the Mets superstar, his 145 is 28 more points than Tatís’ 117. I tend to look at DRC+ more when it comes to valuing offense. However, I have always taken issue with DRC+ when it comes to how they grade speedsters and singles hitters. Alonso is given major preference points for hitting home runs while Tatís is hindered by his tendency to leg out singles and do more damage once he is on base.

Being that Alonso is the first baseman and Tatís is the shortstop fielding is very important. FRAA puts Alonso ahead at 2.0 to 1.0, while DRS has both players dead even at 0, and UZR is much more of an Alonso fan as his 1.1 beats out Tatís’ -1.1. None of the stats like Tatís as a fielder, but a lot of that can be chalked up to him playing a more demanding position and his tendency to make mental mistakes on balls that he should be able to easily handle. It’s not that Tatís will be an amazing fielder, everything points towards him being average, but Alonso is an average first baseman at best and an average shortstop is worth far more than an average first baseman every day of the week.

Now, when it comes to WAR this isn’t much of a competition. bWAR has Alonso at 2.9 and Tatís at 2.5. rWAR likes the Mets slugger for 4.0 and the Padres stud infielder for 3.3. fWAR also gives it to Alonso, 3.6 to 3.0. This is the moment when you probably think it’s become a slam dunk for Alonso and the national writers are correct. Unfortunately, a major problem is that Tatís has only played in 55 games and amassed 234 plate appearances, while Alonso has seen action in 89 games and appeared at the dish 376 times. If Tatís stays healthy ZiPS expects him to finish with an fWAR of 3.9 and PECOTA sees a bWAR of 2.0. On the other hand, Alonso is projected to finish with 4.9 and 3.8 respectively.

Projections are projections, and they can be wrong. For Tatís hopefully they are wrong, and I will admit that his projections feel a little on the light side. Still, as much as Padres fans have made a huge deal about Tatís belonging in the discussion, and he does, the NL RotY is Alonso’s award to lose. I fully expect him to win the award and rightfully so. At the same time, I expect Tatís to have the better career, but that’s not what this article is about. This year, using the stats and our eyes it is evident that both are putting together terrific seasons but that Pete Alonso is putting together the award-winning season.

Lead photo courtesy of Paul J. Bereswill – New York Post

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Bill Thompson
Father (human/feline/canine), husband, Paramedic, Socialist, writer Internet Baseball Writers Association of America and Off the Bench Baseball; freelance writer at various online and print publications. Member Internet Baseball Writers Association of America & Society for American Baseball Research.

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