Hm. Balance spec. FiB, Sever Force, Force Breach, Double Strike, Saber Strike, Spinning Strike, Shadow Strike, mind crush, and project(though in pve I find myself using it less in favor of better force management). That's nine abilities I use in my pve spec for a rotation with project being a variable. This only grows in pvp when you add in other abilities such as slow into the mix. So while it may be almost 10+ in pve it grows to be more than ten in pvp due to using force slow as part of the rotation which should be used a lot. Then add in other abilities a pvp DPS should use such as our stun, interrupt, resilence, etc and we surpass 15 abilities that should be used in pvp. I realize that they are not all pure DPS abilities and a pvp rotation tends to be situational but all these abilities and others are essential to being a good pvp dps (however shadow strike is purely my choice in build). I should also note that some abilities such as mind snap are usually needed in pve also. So, sorry. You apparently don't know much about balance specced shadows.
Also like the other poster noted, he was counting defensive abilities. So he actually was under the amount.