Many saw Mark Appel as the odds-on No. 1 overall pick in last month’s First Year Player Draft.  Signability concerns, however, caused his stock to slip, and the tall, athletic RHP out of Stanford fell to Pittsburgh at No. 8 overall.  In retrospect, he should’ve fallen further, as Appel refused a signing bonus worth $3.8 million, opting to return to Stanford for his senior season.  Must be frustrating for Pirates fans.  A larger offer from the club would’ve forfeited their 1st-round pick for 2013 under the new CBA terms.  Instead, their first selection for 2012 was for naught.  With arms like Jameson Taillon and Gerrit Cole already in their minor league ranks, the addition of Appel would’ve given Pittsburgh one of the most impressive collection of starting pitching prospects in the game.  Certainly much of the frustration here needs to be directed toward MLB’s new draft slotting system.  After paying above-slot bonuses to several later-round picks, the Pirates were handcuffed when it came time to negotiate with Appel and his agent Scott Boras.  Still, better foresight from Pittsburgh a month ago could’ve avoided this unfortunate situation.  Appel should be near the top of next year’s class once again.  For more on him, here’s a brief scouting report I wrote pre-draft.