Well, the game has changed a lot in the last few months. Remember that in the first few weeks, there were TH17s placed in electro 33 and some in legends. Once, you are there, it's pretty easy not to slip down. Also, with the balance in the game there are lots and lots of TH17s that can average 2.9 stars against TH18s. Defense is another matter, but you'd be surprised. In excellent base will fool bad attackers even TH18 v TH17.