Now that Paul Pierce is the toast of trade rumors everywhere, the Celtics are close to that inevitable point. The team has to at least think about replacing arguably the most explosive scorer in franchise history — a player who will ultimately be known as a top-five Celtic. The only problem is the C’s aren’t going to find that player in Thursday night’s NBA draft. The small forward field is relatively thin, with Georgetown’s Otto Porter the only member of this category headed for the upper half of the lottery. Porter may be the only small forward to crack the lottery, period. Questions about Shabazz Muhammad’s character as well as his jump shot may slide the UCLA forward right into the Celtics’ slot at No. 16, leaving them with an interesting choice. But if president of basketball operations Danny Ainge really does want to consider drafting a small forward, there will be plenty for the taking when the Celtics are on the clock. Quality is shallow in this category, but not the mid-first-round options. THE CREAM OTTO PORTER, Georgetown 6-8, sophomore — 16.2 ppg, 7.5 rpg He’s wiry as opposed to bulked, but that isn’t going to scare anyone off. Porter is the sleeper of the top five players in this draft. He could easily go to Washington with the third overall pick. The Wizards backcourt considered, frontcourt scoring is their next logical move, and Porter projects as a smooth scorer in this league for a long time. In a draft clogged with point guards and shooting guards, he’s also the only lottery-worthy small forward available. CELTICS POSSIBILITIES L SHABAZZ MUHAMMAD, UCLA, 6-6 freshman. Relevant stats: 17.8 ppg, 5.2 rpg. He could go anywhere from the mid-lottery to the middle of the first round. No one seems to be sure, and as such Muhammad is an early favorite to take the biggest slide on Thursday night. He’s a slasher, and absolutely one of the highest-rated scorers in the draft. But there are serious questions about his shooting ability. His main attribute, though, is the ability to create his own shot. He’s not an assist guy, and don’t even start on defense.