I can’t imagine many readers of this site don’t know about Baseball-Reference’s Play Index, but in case not, know that it represents one of the great joys of being a baseball fan for those interested in mining baseball's past and present. The recent addition of Sean Smith’s historical WAR data has only made the Play Index that much more enjoyable. In a recent guest post I wrote at Wezen-Ball on Red Sox Hall of Famer Fred Lynn, I searched for the greatest individual seasons by Red Sox and sorted by WAR. The results were surprising, and so I decided to play with it some more. What follows are some of the more surprising items that caught my eye. I will follow up with a National League piece tomorrow.

Let’s stick with the Red Sox for starters. In 1995, they won the American League East and first baseman Mo Vaughn won the American League Most Valuable Player award. While it may not rival 1987’s George Bell over Alan Trammell sham, it was an awful choice. Albert Belle was much better than Vaughn and among stat-friendly types the 1995 vote goes down as one of the worst in recent memory. It’s hard to see how anyone could have believed Vaughn was better than Belle, Edgar Martinez or even Tim Salmon that season.

But that’s old news. What caught my eye as I sorted through the greatest individual Red Sox seasons of all time (as determined by WAR), was that another Red Sox, one of Vaughn’s teammates, appeared to have had a much stronger MVP case than Vaughn, too. John Valentin’s 8.5 WAR season, the strike-shortened season of 1995 no less, stands today as one of the finest years a Red Sox player has ever posted and wouldn’t you know it, the highest total in the AL for that year.

Valentin hit .298/.399/.533 while playing a very good shortstop for Boston that season. I want to be careful not to ascribe too much value to WAR since Valentin derived so much of his value that season from his fielding, an area of the game more easily quantified today than ever before but still inexact nonetheless. Still, you could imagine my surprise when Valentin’s name appeared so high on the list of all-time great Red Sox seasons, and atop the American League for 1995.

Perhaps the most surprising team list of all is the Angels. Here are the top individual seasons in Angels history:

               Season  WAR
Jim Fregosi     1964   8.1
Darin Erstad    2000   7.7
Jim Fregosi     1970   7.7
Troy Glaus      2000   7.6
V. Guerrero     2004   7.4

Nothing against Fregosi or Erstad but for a proud franchise like the Angels with a particularly strong recent history of success, one would just think that names with more zing than Fregosi or Erstad might sit atop their best ever list.

The Yankees’ list is just absurd. When purists or others criticize a stat like WAR, I like to urge them to check out some of the results and see if it aligns with their impressions of who the best players are. I realize this post is about surprises, but the Yankees’ list is surprising in its ridiculous predictability. The top 25 seasons ever recorded by Yankees is an exclusive list of just six players: Babe Ruth, Mickey Mantle, Lou Gehrig, Rickey Henderson, Alex Rodriguez and Joe DiMaggio. It’s almost as if WAR might be a reasonably accurate measure of a player’s value!

Speaking of Henderson, did you know that Jason Giambi has the 4th best season in A’s history, trailing only Eddie Collins and Jimmie Foxx, and better than any season Rickey notched in an Athletics uniform? Or that Reggie Jackson’s 9.7 WAR season in 1969 was the 3rd best A’s season in the last 50 years (trailing only Giambi and Rickey) and also the very best of his career? I hadn’t realized Reggie’s best year came so early on in his career. Go check the A’s list out for yourself! There’s a lot there.

To give you a sense for just how futile Seattle Mariners baseball was before the arrival of Edgar Martinez and Ken Griffey Jr., only one of their top-42 seasons by WAR pre-dates the duo’s arrival. Alvin Davis’s 5.6 WAR season in 1984 ranks as the 23rd best season by a position player in Mariners history, and is the only season to appear in the top-42 before 1990.

Ben Zobrist holds the Rays all-time single season WAR record, with his 7.1 figure in 2009. Amusingly for this Red Sox fan, Julio Lugo appears on the Rays top-10 list. Chalk it up to their short history, sure, but there were also some mighty lean years down in St. Pete.

Finally, to tie it all together, we get to the Blue Jays. There are many players and seasons on their list before you get to 1987 MVP winner Bell. Among others, some of the least distinguished you’ll find include Lloyd Moseby, Devon White, Marco Scutaro and Aaron Hill. They may not be baseball royalty, but they all had better seasons than the 1987 American League MVP winner!

I urge everyone to check out the Play Index, and specifically to play around with the WAR lists. It’s simultaneously fun, shocking and enlightening, and will only enhance your enjoyment and appreciation of baseball’s best and most memorable players and seasons.