Close calls with offsides happen, when its goes really quickly and is quite narrow call, like OUR offside goal (so we benifited from a mistake as much as Inter did this week, regardless if we won 3-1 and they 2-1), and few others that regurarly happen.
But this offside call is absolutely terrible mistake because the guy passing forward to Maicon IS in line with Siena's defence, OFCOURSE anything forward from that is offside, which Maicon was. Just like how RVPs offside goal against Chelsea was absolutely terrible call. Really beyond imcompetent refereering, not the kind that can be given leeway when its understandably close or such.