How good is Buster Posey?

A great start to a career is no guarantee of greatness. I submit exhibits A and B - Fred Lynn and Pablo Sandoval.

We have yet to see what Buster Ballgame can do while fully healthy for a full season. He played 108 games his rookie season, then 45 games in 2011 before his injury. In 2012 Posey played 148 games, but he spent time rehabbing on the fly and shaking off the rust.

What if the real Buster Posey is the guy who hit .385 after the All-Star break? That's unlikely, but you never want to sell Buster short.

The point is, Posey is still so new that we just don't know how unreal he is.

Lynn was the AL Rookie of the Year and MVP for the Red Sox in 1975 at age 23, hitting .331 with 105 RBIs. Lynn played 15 more seasons and, aside from similar numbers in 1979, never again drove in more than 86 runs and nudged over .300 just two other times.

Sandoval, an even bigger (literally and figuratively) unknown quantity than Posey, kicked off his career hitting .345 (in 41 games), then .330, a start that projected to Cooperstown, but Panda veered off toward Palookaville. A bust? Maybe, although the real Sandoval could be the one who tore up the playoffs and World Series.