If you take out the top tier of Cobb, Mays, Speaker, Mantle, and DiMaggio, Beltran slides in pretty favorably with the remaining Hall of Famers. (I threw in Junior for reference and since he is an obvious first-ballot Hall of Famer.)
Also, WAR and dWAR are compiled counting stats, which means that if Beltran has a few more good years (let's say 5-6 pretty good years) he could pass Junior in WAR and has an outside chance to pass DiMaggio. On the other hand, he's now playing RF which makes it harder to compile value, so that seems unlikely. I'm not saying Beltran should definitely be in the Hall of Fame or anything, but it does show how underrated he has been. He comes out #3 on a list of 18 HOF CFs in defensive value, and #9 on a list of 18 HOF CFs in overall value; and still hasn't finished his career yet.
Ty Cobb 159.4 WAR, 3.4 dWAR
Willie Mays 154.7 WAR, 18.5 dWAR
Tris Speaker 133 WAR, 11 dWAR
Mickey Mantle 120.2 WAR, -1.9 dWAR
Joe DiMaggio 83.6 WAR, 4.7 dWAR
Ken Griffey Jr. 80.8 WAR, -2.3 dWAR
Billy Hamilton 69.6 WAR, 0.9 dWAR
Duke Snider 67.5 WAR, -2.1 dWAR
Carlos Beltran 58.3 WAR, 8.1 dWAR
Richie Ashburn 58.0 WAR, 6.9 dWAR
Max Carey 50.6 WAR, 7.9 dWAR
Hugh Duffy 49.6 WAR, 5.0 dWAR
Larry Doby 47.4 WAR, 1.6 dWAR
Edd Roush 46.5 WAR, -0.2 dWAR
Earl Averill 45.0 WAR, -4.0 dWAR
Kirby Puckett 44.8 WAR, -1.8 dWAR
Earle Combs 44.7 WAR, 1.0 dWAR
Zack Wheat 57.8 WAR, 6.2 dWAR
Hack Wilson 39.1 WAR, -3.2 dWAR
Lloyd Waner 24.3 WAR, 1.4 dWAR
Boom. Thoughts?