(First in a series looking at the Detroit Lions’ positional needs for the NFL draft which begins on Thursday. Today the defensive line.)

  Defensive end is without question one of the Detroit Lions big needs heading into the draft. The starters from the last three seasons will not return. Kyle Vanden Bosch was released, while Cliff Avril signed as a free agent with the Seattle Seahawks.

  Jason Jones was signed as a free agent and is expected to start on the left side in place of Avril. Willie Young returns and could compete for Vanden Bosch’s spot. Lawrence Jackson has not been re-signed. Not much depth at defensive end either.

  With the No. 5 overall pick the Lions could address the situation right out of the gate.

 Several draft experts including Charley Casserly of NFL.com and Dane Brugler of CBSSports.com have the Lions drafting Ezekiel “Ziggy” Ansah out of BYU in the first round. 

   Ansah, who is 6-foot-5 and 271 pounds, is intriguing and raw.

   “You're not sure what you're going to get, but you know there is a potential for this huge upside. I think it's the best story in the draft. I really do. A year and a half ago, a year ago, he was not even on NFL team's draft boards. Now we're talking about him as a Top 10 selection who has played minimal snaps. It scares me, and it scares teams how little he has played,’’ NFL Network draft analyst Mike Mayock said in a conference call on Thursday.

  Ansah was a situational player at BYU in 2010 and 2011, his first two years of organized football. A full-time starter in 2012 — lining up as a rush outside linebacker, defensive end and defensive tackle. He had 62 total tackles, 13 for a loss, including 4.5 sacks. He also notched nine pass breakups, one forced fumble and one interception.

  The Lions had a chance to get to know him well at the Senior Bowl. Ansah played on the South team which Lions coach Jim Schwartz and his staff coached.

  The consensus is that he was average in practice during that bowl week, then turned heads and opened eyes during the game.

  “He was the best player in the game. So there is this tantalizing upside that's going to push him up pretty high,’’ Mayock said. “But I would tell you, Jason Pierre-Paul is a guy a few years ago that had this unbelievable upside, but he wasn't as raw. He's really raw. But what I like about Ziggy is he plays hard. I think he played a little out of position at BYU, and I think he's much more comfortable out wide from what I saw in The Senior Bowl.’’

 (Pierre-Paul was the New York Giants first-round pick in 2010 and was a Pro Bowler in 2011 and 2012.)

  Dion Jordan (6-foot-6, 248 pounds) out of Oregon is also considered a top 10 pick and made a pre-draft visit to the Lions.  NFL.com draft analyst Mike Tannebaum has Jordan going to Lions in his mock draft.  

  The pass-rushing specialist put on a clinic at the NFL Combine running a 4.60 40-yard dash. Since then he had surgery for a torn labrum.

  If the Lions don’t draft Ansah or Jordan in the first round, they can look to later rounds.

   Bjoern Werner (Florida State) could be available for the Lions with their second-round (36th overall) pick. ESPN draft analyst Mel Kiper thinks he would be a good fit for the Lions at that pick if they opt for another position in the first round.

  Werner’s stock has dropped although NFLDraftScout.com ranks him as the second-best defensive end in the draft.

  Opinions vary widely on Damontre Moore (Texas A&M) whose work habits are a concern to some. NFL.com analysts Brian Biillick (former Baltimore Ravens coach) and Scott Pioli (former Kansas City Chiefs general manager) have Detroit drafting him in the first round.

   Michigan State’s William Gholston should be available if the Lions wait until the third round. He and Jordan were the only two defensive ends who made official pre-draft visits with the Lions.

 “Gholston, to me, is intriguing, because he can play 4-3 base end. Or the 3-4 teams will like him as a five-technique. So with his size and his body, I think he's one of those guys, ends up in the right team, he'll be a better pro than he was in college,’’ Mayock said. “I can see him going in the third round.’’

  Other later round possibilities include Margus Hunt (Southern Methodist) who is an Estonia native who has played football just since 2009 and John Simon (Ohio State) who is smaller at 6-foot-2 and 257 pounds, but was the Big Ten defensive player of the year in 2012.

  Kiper and Mayock both like Simon’s athleticism.

 “I like the way (Simon) plays the game,’’ KIper said. “He’s got a lot of versatility. He plays with energy. You look at John Simon, you think early to mid third round. I project him to Buffalo, 71st pick overall. Energy, kind of like the old Mike Vrabel who came out of Ohio State, had a nice career in NFL. Play down end, gives you some scheme versatility. Great kid. Tremendously hard worker, great passion for the game. I think John Simon solidly in the third round now.’’

  Even if the Lions draft Ansah or Jordan in the first round, they could look to add depth at the position in later rounds.

  The Lions have a pick in each round with two picks in the seventh round. The NFL draft starts at 8 p.m. Thursday with the first round. It continues at 6:30 p.m. Friday with rounds two and three, and wraps up starting at noon Saturday with rounds four through seven.

 (Follow @PaulaPasche on Twitter. Order her book,  “100 Things Lions Fans Should Know & Do Before They Die’’ here. It’s also available at bookstores.)