At this writing, Dodgers rookie shortstop Corey Seager is in the midst of an 19-game hit streak. Over that span, he's batted a robust .392/.448/.646, which is obviously a high level of production. Of course, Seager wasn't exactly scuffling before his current streak began. At the close of his last hitless game on June 15, Seager was hitting .275/.337/.504. Throw in that streak, and Seager's batting .303/.363/.537 while playing in 86 of the Dodgers' 87 games to date. Needless to say, that's outstanding production, especially by shortstop standards.
Speaking of shortstop standards, the 22-year-old Seager is also grading out exceptionally well by historical standards. Right now, Seager has an 17 home runs, an OPS+ of 142 (this is simply OPS adjusted to reflect park and league conditions -- it's scaled so that a mark of 100 is league average, and the higher the mark the better), and a Wins Above Replacement (WAR) of 3.4. Now let's put some of those in perspective.
Among rookies to play at least 50 percent of their games at shortstop, Seager already ranks 10th in home runs. His NL West shortstop peer, Trevor Story of the Rockies, is eighth on the list with 19 homers. The record for home runs by a rookie shortstop belongs to Nomar Garciaparra, who hit 30 for the Red Sox in 1997. Right now, Seager is on pace for 32 spanks this season, and Story is in line for 37. Let it be said, though, that since Story in the first four games of the season, Seager has out-homered him by a margin of 17 to 13.
As for Seager's current OPS+ of 142, if it holds then it would be an all-time record among rookie shortstop since 1901 by a comfortable margin. In his 2015 AL Rookie of the Year campaign, Carlos Correa put up an OPS+ of 132, but he did so across just 387 plate appearances. Seager should top that PA total later this month. Among qualifying rookie shortstops, Garciaparra's 1997 mark of 123 is the record. Seager has room to decline and still best that mark. As for Story, his current OPS+ checks in at 106. Let is also be said that Cardinals rookie Aledmys Diaz (12 home runs) is also running an OPS+ of 142, so consider him to be part of this "rookie shortstop OPS+" discussion, as well.
As for WAR, which of course provides a thumbnail measure of a player's overall value (i.e., his batting, fielding, and base-running), Seager's present mark of 3.4 ranks ninth all-time (Story's at 1.5, and Diaz has a 2.5 WAR). That puts Seager on pace to register a 2016 WAR of 6.3. If that comes to pass, then it will rank second only to Troy Tulowitzki of the Rockies in 2007 (6.8 WAR) and Garciaparra in '99 (6.6 WAR). That certainly puts Seager within range if he somehow manages to get even better in the second half. As well, there's some imprecision to WAR, so Seager's current pace will at least put him in the discussion for best rookie shortstop ever.
So, yes, the Dodgers certainly seem to have a present and future franchise cornerstone in their midst. Given Seager's high draft standing (18th overall pick in 2012), impressive minor-league dossier (he was a consensus top-50 prospect going into 2014, a consensus top-10 prospect going into 2015, and the by-acclamation top overall prospect coming into this year), there's no other conclusion to be reached.
