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Stanford's Mark Appel pitches in the sixth inning at Klein Field at Sunken Diamond in Stanford, Calif. on Friday, June 1, 2012. The Stanford Cardinal played the Fresno Bulldogs in the first round of the NCAA Stanford Regional. (Jim Gensheimer/Staff)

Stanford ace pitcher Mark Appel, a first-round pick of the Pittsburgh Pirates, is reportedly strongly considering returning to the Cardinal and re-entering the draft next year.

CBSSports.com's Jon Heyman reported that Appel is "leaning against" signing with the Pirates. The deadline for draft picks to sign with MLB teams is 2 p.m. PT Friday.

Appel, who was drafted by Pittsburgh with the No. 8 overall pick last month, has thus far turned down the Pirates' reported maximum offer of $3.8 million. Due to new MLB draft rules, if Appel signs for more than $3.8 million, the Pirates will be stripped of their 2013 No. 1 pick.

However, if Appel eschews Pittsburgh's offer to stay at Stanford, the Pirates will get the No. 8 overall pick in next year's draft -- in addition to their other 2013 first-round pick.

Appel is one of six first-round picks from the June draft who have yet to sign.

Appel, a former Monte Vista High star, was a second-team All-America team selection after going 10-2 with a 2.56 ERA in 16 starts for Stanford. The right-hander led the Pac-12 during the regular season with 130 strikeouts in 123 innings.