Steve Sullivan comes from the Pittsburgh Penguins where he played 79 games and was 17-31-48. His season started off a bit slow though, he did not light the lamp until his 15th game. With the shortened season he is going to have to be better though. Sullivan may have found it difficult adjusting to the Penguins style having played the last 6 seasons with the Nashville Predators (missing one season for the 04-05 lockout and one due to back injury), and if that was the case hopefully the Coyotes style will fit his play better.
Of the new additions, Sullivan has the biggest responsibility. He will likely be replacing former Coyote Ray Whitney on the top line, and he will also hopefully be adding some life to the Yotes' lackluster power play.
Zbynek Michalek, or Z for short, is a returning Coyote, having played 5 years with the Desert Dogs. He spent the last 2 years playing in Pittsburgh before being traded on Draft Day back to Phoenix for Harrison Ruopp, Marc Cheverie, and a third round pick. You probably won't expect to see much offense out of Z, although his career high goals, assists, and points did come as a Coyote, but what you get is a great defenseman who will likely be paired with Oliver Ekman-Larrson. Michalek's skills extend off the ice. He was an assistant captain during his first stint as a Desert Dog.
David Moss had up until this year only played on one team at the NHL level, the Calgary Flames. After a few injuries which he has recovered from he decided that it was time for a fresh start and signed a 2 year deal with the Yotes. Moss will probably have a lot to prove to his new club, and despite his numbers last season he has potential to be a 20 goal scorer. Hopefully he can stay healthy during the shortened season, but having played one of his best seasons in only 58 games, 17-13-30 in 2010-11, he has potential to give the offense a boost.
Nick Johnson comes to the Coyotes from the Minnesota Wild by way of the Pittsburgh Penguins. He was originally claimed off waivers by the Wild. He signed a one year two-way deal with the Coyotes during the offseason. Johnson played a career high 77 games with the Wild last season where he was 8-18-26, so don't expect to see too much offense from the Calgary native but he could hopefully add something to the Coyotes fourth line. GMDM seems to see potential in him.