I think teams "parking the bus" was definitely an issue from 2008 up to the start of last season. However since then I really don't think many teams have approached games at WHL like this. In the first 4 or 5 games of last season teams were sussing us out post-Bale and tended to sit in with two banks of four. But with no pace at the other end to stretch teams on the break, and the fact we played dull, lifeless football which had no end product, I thought the opposition began to take us on.
A lot of the problems were (and possibly still are) down to our own making. Our tempo especially at the start of games has been extremely slow for the last 18 months. Certainly some of the defeats this season haven't been due to teams sitting & defending for 90 mins. Stoke came and played football and attacked us, Saudi Sportswashing Machine played well in the 2nd half (although offered nothing 1st half including no defensive resilience), West Brom also came and attacked even though it was only a 1-0 they had more chances than us on the day. Even the Palace game they could and should have won because they came out and attacked us. In each of these games we couldn't string 3 passes together and didn't deserve anything - I didn't see evidence of busses being parked!
Thankfully since the Everton game in November (Palace game above excepted) there are clear signs that we are beginning to rectify this, no doubt due to the emergence of the starting XI we have now.
A quick tempo and good movement will pull all manner of teams apart and we are seeing that from the front 4 now.