2008-09: Bill Arnold skated for the Little Bruins prior to the high school season and tied for the team lead in scoring for Nobles and Greenough (Mass.). He scored 26 goals with 21 assists in 33 games for the Little Bruins. In 29 games with Nobles and Greenough, he scored 28 goals with 27 assists.
2009-10: Arnold played for the US NTDP team that competed in the USHL this season. In 26 games, Arnold scored 8 goals and added 15 assists for 23 points. He posted a +15 rating for the season.
2010-11: Arnold had a very good freshman season at Boston College, scoring ten goals with ten assists and a plus ten rating in 39 NCCA (HE) games. He centered the Eagles’ third line while being used on both the power play and penalty kill units by the season’s end. The freshman was named to the NCAA (Hockey East) All-Rookie Team for the 2010-11 season.
2011-12: Arnold was one of the top forwards for NCAA champion Boston College as a sophomore and was impressive playing for the USA at the 2012 U20 World Junior Championship. He scored 17 goals with 19 assists and was plus-16 with 46 penalty minutes in 42 games for the Eagles. Boston College won its final 19 games; capturing the Hockey East regular season and playoff titles and defeating Ferris State, 4-1, in the Frozen Four Final. Arnold was one of the few forwards to stand out for the USA team; scoring 3 goals with 3 assists in seven games for a team that finished seventh.
2012-13: Arnold was the fourth-leading scorer for Boston College in his junior season. The center scored 17 goals with 18 assists and was +5 with 40 penalty minutes. The Eagles finished second to Massachusetts-Lowell in Hockey East and received an at-large bid to the NCAA tournament after a loss to Boston University in the Hockey East semifinals. BC lost to Union, 5-1, in the NCAA East Regional semifinals.
2013-14: Arnold signed a two-year entry-level contract with Calgary in April 2014 following his senior season at Boston College. He made his NHL debut in an April 13th game against Vancouver, finishing -1 with no points nor penalties in 13:35 minutes of ice time in his only NHL game. Skating on one of the top lines in college hockey with fellow Flames’ prospect Johnny Gaudreau and future New York Ranger Kevin Hayes, he scored 14 goals with 39 assists and was +43 with 51 penalty minutes. BC won the Hockey East regular season title and was among the top-ranked teams in the country most of the year. The Eagles were upset by Notre Dame in a three-game Hockey East quarterfinal series but rebounded to capture the NCAA Northeast Regional — defeating Denver and Massachusetts-Lowell — before falling 5-4 to eventual national champion Union in a Frozen Four semifinal game.
2014-15: Arnold skated for Calgary AHL affiliate Adirondack in his first pro season. He was the club’s fourth-leading scorer despite missing 15 games after suffering a separated shoulder in February. Skating on the Flames’ top line with Emile Poirier for much of the year, Arnold scored 15 goals with 23 assists and was +2 with 30 penalty minutes in 61 games. The Flames missed the AHL playoffs, finishing fourth in the North Division. Calgary re-signed Arnold to a one-year contract as a restricted free agent in July 2015.
Arnold is a hard-working center with some offensive instincts who can play the defensive shutdown role. He puts up solid offensive numbers by driving hard to the net in the attacking zone. Arnold is a physical two-way center with great character and an excellent work ethic. He is solidly built and has greatly improved his skating since his early college days but must continue to add mobility to compete at the NHL level. He can play on both specialty teams. Arnold has the hockey smarts to exploit his opponents’ weaknesses and recognize where his wingers are on the ice.
Arnold will compete for a lower line center slot with the Flames in his second training camp with Calgary but with the team's depth he will likely start the 2015-16 season with new AHL affiliate Stockton. Arnold made a smooth transition from college hockey to the pro level in his first season with the AHL's Adirondack Flames last season and would be one of the team leaders if he is with the Thunder this year. Long-term, Arnold projects as a top-nine NHL forward with some offensive upside, though he may lack some skating quickness and the overall skill level to play at that level on a permanent basis.