Expected to go first overall, Stanford right-hander Mark Appel fell to the Pirates at No. 8. (US Presswire)

Stanford right-hander Mark Appel -- the projected No. 1 pick who fell to 8th in last month's draft -- did not sign with the Pirates at Friday's deadline. He will return to Stanford for his senior season, as he and his advisor, Scott Boras, had threatened. The Pirates will receive the No. 9 pick in next year's draft as compensation. He was the only first-rounder who didn't sign.

"After much thought, prayer and analysis of both opportunities, I came to the conclusion the best decision is to remain at Stanford continuing my studies, finishing my degree, and doing all I can to assist the Cardinal baseball team in our goal to win a national championship," Appel said in a statement. "I greatly valued the prospect of a professional opportunity and I will pursue a professional baseball career after getting my Stanford degree. I appreciate the love, support, and guidance from everyone who helped me make this decision."

Earlier Friday, CBSSports.com Insider Jon Heyman reported it was unlikely Appel would sign. Pittsburgh had reportedly offered a $3.8 million signing bonus -- $1 million less than top pick Carlos Correa of the Astros and $900,000 more than the suggesting slot bonus of $2.9 million. Pittsburgh had a draft cap of $6.56 million and spent $2.58 million on its 16 picks.

"We were unable to reach an agreement with first round selection Mark Appel and bring him into our already strong organization," Pirates general manager Neal Huntington said in a statement released by the team. "Our final offer exceeded the available bonus pool money and was essentially up to the last dollar we could offer prior to falling into the second tier penalty which would have resulted in the loss of a first round draft selection. While, as we have shown in past years, we are willing to be aggressive with our financial offer, we simply did not feel it was in the best interest of the organization to forfeit our first round selection in the 2013 amateur draft.

"Selecting Mark was a calculated risk, as we knew he would be a difficult sign. As an organization, we need to continue to take these types of calculated risks. While we would’ve preferred to add Mark to the group of talented prospects in our system, we wish Mark, and his family, nothing but success in the future."

The Nationals were able to agree to a deal with California high school right-hander Lucas Giolito late in the process, CBSSports.com Insider Jon Heyman confirmed. Jim Callis of Baseball America tweeted the Nationals gave Giolito a signing bonus of $2,925,000.

Also signing near the deadline was No. 5 pick, right-hander Kevin Gausman of LSU. According to Heyman, Gausman received a signing bonus of $4.32 million. Gausman tweeted the news of his signing with Baltimore just after the 5 p.m. ET deadline for picks to sign:

Earlier Friday afternoon, the Rays announced the signing of Clemson third baseman Richie Shaffer, the 21st overall pick. Shaffer received a signing bonus of $1,712,500, according to Callis.

Friday morning, the Marlins agreed to a deal with left-hander Andrew Heaney, the ninth overall pick. Heaney, from Oklahoma State, will received a $2.6 million signing bonus.

Late Thursday night, the Yankees signed New Mexico right-hander Ty Hensley for a $1.2 million bonus. The two had agreed to a $1.6 million bonus, but an MRI showed an abnormality in his right shoulder, sending the two sides back to negotiations.

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