Most 92's have a +/- that is negative unless they are playing for a top team. Depends on their ice-time. Spooner was -16 and Quesnel was much lower. Spooner plays a regular shift on 2nd line, whereas Quesnel is 4th line at the moment and only gets 3 - 6 shifts per game.
MacFarlane obviously plays a regular shift also and therefore gets more icetime. If a rookie is playing against opponents that are 2 or 3 years older they will face some challenges. In the case of Spooner, battles in the corner are challenge due to his size. Whereas other 92's that are bigger like Kassian was last year can handle all the physical aspects of the game.
Any 92's playing a regular shift are very fortunate considering it is their 1st year in the league. Also keep in mind, that your +/- is dependent on who you play with and against. If your on the 2nd line and not playing at home to use the last change advantage, you could be matched up against the opponents #1 line.
Not always exact science, but can pose challenges for younger players.