PITTSBURGH -- Wyatt Mathisen, the high-upside catching prospect taken by the Pirates in the second round of this week's First-Year Player Draft, is the first of Pittsburgh's high-profile draftees to sign.

The Pirates on Monday officially confirmed the agreement, which had already been reported by multiple online sources -- including Mathisen himself.

"Crazy that I'm going to start my job on Tuesday!" Mathisen posted on his Twitter account on Sunday evening.

Pirates Prospects, a website dedicated to the organization's up-and-comers, was the first to report the agreement, which Baseball America later in the day said was for the exact slot amount for a second-round pick: $746,300.

"The Pirates are excited to add the offensive and defensive skill set of Wyatt to the organization," Pirates director of amateur scouting Joe DelliCarri said in the team's statement. "He possesses the ability to be a quality catcher and a solid offensive producer from the catching position. His grounded foundation and passion for the game will serve him very well on his journey through baseball."

The signing means the Pirates will not have any bonus surplus with which to sweeten the pot for Mark Appel, the Stanford right-hander who was their top pick on Monday as the overall No. 8 overall choice and has been portrayed as a "tough sign."