The Pittsburgh Pirates say they were unable to sign first-round draft pick Mark Appel despite offering him as much money as they could afford.

Appel, a standout right-hander at Stanford who was projected as the No. 1 pick in the draft, instead fell to the Pirates at No. 8 likely because of worries about his signability.

He will be a senior at Stanford next season. The Pirates will have the No. 9 selection in next year's draft as compensation for not being able to sign him.

"Selecting Mark was a calculated risk, as we knew he would be a difficult sign," the Pirates said in a statement Friday. "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 Pirates said their final offer exceeded the bonus pool money they had available "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," the Pirates said, "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."

The Houston Astros selected infielder Carlos Correa from the Puerto Rico Baseball Academy with the No. 1 pick instead of Appel, who is represented by superagent Scott Boras.