The I here is mostly I2-Din, i.e., I2a1b. Additionally, you have some R1, it isn't specific about how much R1a, but I've seen other studies going from 9 to 16%. Meaning it's beyond doubt that you have at least around a third or more Slavic Y-DNA in Tosks. When you also take into account that South Slavs aren't exclusively I2-Din and R1a, it means that the genetic contribution of the Slavs in South Albania in terms of Y-DNA was even greater than a third. Every Tosk has a Pyotr, Dima and Vadim inside of him.
http://4.bp.blogspot.com/_Ish7688voT.../albanians.png