Let's compare new Hall of Famers Ken Griffey Jr. and Mike Piazza's scouting reports

Some scouting reports are more notable for what they missed than what they saw, but some scouts can see the future, especially when it's showing off its sweet swing right in front of them:

Steve Vrablik was a Mariners scout in 1987, and he knew what was coming. Here's his scouting report on new Hall-of-Famer Ken Griffey Jr.:

Vrablik wrote this report as though he used his TARDIS to check that all of his conclusions turned out right. He predicted Junior would eventually reach an "8" power rating, and the center fielder's 630 career home runs bear him out. He said he had "above [average] to outstanding tools in all [five] categories" and "very good instincts in the [outfield]."

And though he noted his prospect was the son of then-Braves player Ken Griffey Sr., he wrote "#1 Pick in the Nation" on the line for "Parents Name." That's how good The Kid was. Baseball itself created him. Since he was time-traveling anyway, we don't know why Vrablik didn't just write "will definitely set record by being voted into HOF with 99.3% of ballots (don't ask me how I know this)."
But while some people might see "HOF" in the stars the night some players are born, it's not that way for everyone. Here's a scouting report from Brad Kohler, about some guy named Mike Piazza, who had "no solid [college] offers," and was an "avg. student in class."

But this "avg. student" is the one who gets to do all the bragging at his class reunion. Kohler may not have been as effusive as Vrablik was about Junior, but he did see something in Piazza. "A long way to come with overall ability," he wrote, "but worth selection on bat and [power]." 

However, Kohler also assigned him a future hitting grade of "4," which might not have been the most accurate prediction for someone who ended his career with a .308 batting average and 10 Silver Slugger Awards. He did give him a "6" when it came to future power … so, can all 6-grades do this?