Of Course Steven Souza Is Going to the Rays

Turner, Joe Ross to #Nationals. Myers, Hanigan, Jose Castillo to #Padres. Souza, Ott, Rivera, Smith, Bauers to #Rays (Souza, Ott from Nats).

— Ken Rosenthal (@Ken_Rosenthal) December 17, 2014

Generally speaking, in such cases as a prospect — or any player, really — possesses a combination of power and speed, said player is regarded with some interest by what is referred to broadly as the “scouting community.” While sabermetricians have (in the past, at least) cultivated a reasonable suspicion about such players — or, at least the level of enthusiasm exhibited on their behalfs — it’s also true that those players who’ve both (a) demonstrated power and speed have also generally (b) developed into above-average major leaguers.

Consider: over the 10-year period between 2004 and -13, 96 players recorded both 20 home runs and also 20 stolen bases in the same season. (Or, that is to say, there were 96 such player-seasons during that interval. Some players were responsible for more than one of them.) The average WAR figure among those player-seasons? 5.0, exactly. The number of those players to record worse than a 2.0 WAR (i.e. an average season)? Just four. One find, in other words, that in almost every case where a batter met generally accepted thresholds both for speed and power, that same batter was almost guaranteed to produce wins at an above-average — and frequently a star-type — rate.

Among the 4000-plus projections that have been produced by Steamer this offseason, only three of them call for the relevant player to record a 20-20 season (prorated to 600 plate appearances) in 2015: those for Carlos Gomez, Joc Pederson, and Steven Souza. Gomez, of course, has become of the the majors’ best players. His credentials are beyond criticism at this point. Pederson is a 23-year-old who lacks major-league experience, but also probably would have had a job last spring were he not blocked by the Dodgers’ surfeit of outfielders. Souza, meanwhile, has a decidedly different resume, insofar as he enters his age-26 season this year having recorded merely 26 major-league plate appearances in his whole life — all of them in 2014.

This is odd, insofar as (a) a 20-20 profile strongly suggests the probability of star-level performance, while (b) players who debut in their age-25 seasons rarely become stars.

The latter of those points isn’t a particularly controversial one. To test it, however, I looked at all the players who debuted between 2000 and -04 and proceeded to record at least 1000 major-league plate appearances over the course of their respective careers (mostly to remove pitchers from consideration). I used a sample from the earlier part of the century to guarantee that each player would have had the opportunity to produce roughly a career’s worth of data from which to draw. I then prorated the WAR totals for all players in the relevant sample to 550 plate appearances (denoted as WAR550 below) to get a sense of their per-season talent.

Here are the results of that work in graph form:

Without exception, really, the earlier a player has debuted, the more wins he’s produced on a rate basis. The correlation is pretty strong (r = 0.85). Nor does this fact run contrary to accepted wisdom: promising young players generally ascend through the minors more quickly than not-as-promising ones and also remain productive past their peaks longer than more marginal players.

One finds a similar trend among the game’s most recent and excellent players. For example, over the three most recent seasons only 12 batters have averaged five wins a season or more (which is to say, the average number of wins produced by a 20-20 player, as noted above). The average major-league debut age among those players? 21.8 years old. And the standard deviation? Below two.

That same sample rendered into histogram form:

Only one player who debuted at age 25 (or older, for that matter) has produced 15 wins over the last three seasons. That player would appear to have some relevance to this conversation, however, insofar as it’s Ben Zobrist, a person also employed by the Tampa Bay Rays.

Zobrist’s and Souza’s cases aren’t entirely parallel. Zobrist was drafted three rounds later than Souza (although there’s actually little substantive difference between those two in terms of expected future WAR). Zobrist was a little younger than Souza at the time of their respective trades. And Zobrist hadn’t played above Double-A when he was traded from Houston to Tampa Bay, while Souza has at least appeared in the majors.

There are similarities between the two, as well, though. Among the greatest of them: Zobrist and Souza are both players upon whose weaknesses it’s possible to dwell to the exclusion of their strengths. With regard to Zobrist, for example, there were reasons to dismiss him as an infielder who lacked the ability to play an average defensive shortstop and possessed below-average power. There are, of course, a number of players like that. What the Rays appear to have seen in Zobrist, however, is a versatile defender with elite command of the strike zone. What they’ve ultimately gotten is the second-best player in baseball since 2009.

Souza has also exhibited conspicuous flaws. After playing third and short almost exclusively over the first three years of his professional career, he was moved to first base in 2011 and then, after that, right field. Not an entirely typical path, that — especially for a player who’s averaged 33 steals per 150 games in his minor-league career. Souza hasn’t always made excellent contact, either — and, indeed, that will remain a weakness in his game. What Souza offers, however — the speed, the power, presumably above-average corner-outfield defense (based on his ability to cover ground, if nothing else — is an encouraging package. Steamer agrees: as Dave Cameron noted earlier this afternoon, Souza is projected as a two-win player — roughly equivalent to Wil Myers, for example.

Ultimately, while debut age is a pretty strong indicator of future major-league performance on a macro level, it’s also true that individual players face individual, specific circumstances. Playing on a club that employs Bryce Harper, Denard Span, and Jayson Werth, Souza will have naturally found it difficult to find himself a starting role even this year, as a 26-year-old. As Oakland general manager Billy Beane recently said to Eno Sarris with regard to how new acquisition Joey Wendle had failed to move beyond Double-A in his age-24 season: “That’s not his fault.” Debut age generally is a meaningful indicator of a player’s true talent — except, that is, when it isn’t.