I don't think any one stat tells a complete picture of a player's contribution to the game, or of his Hall of Fame worthiness.
Brock was a unique talent, worthy of his place in Cooperstown. But I don't think if he compiled the same statistics today he would be valued as he was in the 1960s and 1970s. He didn't walk. He was a below average defender. He was caught stealing too often. He produced little power.
But he was a product of his times, compares very favorably to his peers, and was a compiler. I think he also gets favorable treatment from being associated with a historic franchise most of his career, and his end of the Brock for Broglio trade is a fun bit of legend.
As for WAR, I think it works fine for bringing to attention the guys who are overlooked by traditional stats. 19th century pitchers putting up 15+ WAR seasons because they threw so many innings. . .guys like Gene Tenace and Eddie Yost who were OBP machines, superior defenders. . .WAR casts a brighter light on them than they might have otherwise gotten.
Where WAR fails is with any postseason contributions players made. Those are completely ignored. WAR also treats every plate appearance as equal to every other plate appearance, and we know that baseball isn't played that way.
That said, I agree with Sveum that it's a good starting point for discussion. I just wouldn't use it (especially fractions or WAR) as the only way to award MVP, Cy Young and HOF votes.