Just checking on this, but I thought it was 30%. Copied Ben's post.
MI Cabrera, Asdrubal, $0.5m (P-2011)
He's currently the 9th ranked MI which would put him at $9.5M to re-sign, but including the prospect extension discount he can be retained for 9.5 * 0.7 = 6.65 ~ $7.0M. He's only 25 years old and is having a breakout power season, and at a weak position he is certainly worth that salary. However I've got a number of expiring contracts and limited cap room available so I'll need to make some tough decisions.
I believe ben was incorrect on this. Here is the section on prospect extensions in the rule book.
Prospect Extension (went into effect after 2010 season)
Any player who is currently under a prospect contract may be signed to a regular contract extension (see below), but they may also be signed to a prospect extension. Such an extension must be a 5-year deal where the annual salary is
X% of their market value. The resulting annual salary must be no less than $4m. No matter what the current prospect contract is, the prospect extension kicks in the following year at the rate based on when the contract is given.
For the 20XX season, the following percentages would be used per prospect status.
20XX - 60%
20XX+1 - 50%
20XX+2 - 40%
20XX+3, n/a - 30%
There is a window after the season in which the multipliers above are still in effect. This was a rule effective June 16th, 2011 for expiring prospect contracts. Prospect extensions on expired prospect contracts will be the only type of extensions allowable for expired contracts in the offseason. Therefore, after the 2011 regular season is over, a P-2011 contract is still eligible for the prospect extension at the 2011 rate. This window for prospect extensions is open until one week prior to the beginning of offseason free agency.
A 2011 prospect would get signed to 60% of there Market Value. A 2012 Prospect would get signed to 50% of their value. A 2013 Prospect would get signed to 40% of their Market Value. A 2014 or NA prospect would get signed to 30% of their Market Value.
Example can be found here for the Ike Davis Extension.
http://www.profsl.com/smf/index.php?topic=23086.msg116875#msg116875He was a 2013 Prospect and was signed at a 60% discount (40% market value for 2013 prospect).
