From reading this thread about contacting players. I think what i gather from it is that it's not about contacting players from another team to join their team, but rather the timing, and how it was done deceptively. If it was common place why wouldn't teams take each others players or sabotage rivals more frequently. Imagine Hawks convincing 2/3 FCA starting players to come to their team 2 weeks before playoffs start leaving FCA without their starters. If this happens regularly I stand corrected. | 
