Kolo Toure is a good example. In his last season (2008-09) at Arsenal, the side conceded just 12 set piece goals as Toure cleared the ball 129 times, more than any player in the present squad. With Sol Campbell as partner in 2006, the Gunners only gave up 9. Campbell was already 30 years old and Toure five years less. This segues us to crucial aspect of set piece defending - it is a collective effort where each trusts the other to stick to their assignment. In the NFL defensive breakdowns are aptly called "blown coverage". Much of Arsenal's woes can be pointed to someone who forgot to do their job.
The best in the business Nemanja Vidic and Rio Ferdinand have played five seasons together with the former close to 30 and his partner two years older. After this time spent together they epitomize discipline and focus.
Sticking Thomas Vermaelen with a raw 6' 6" centre back is not going to solve matters. Going to the French Ligue for a cut rate bargain is not going to solve the problem of experience and the learning curve. What you need is someone who gives you all these qualities in one package and proven themselves at the highest level. That someone should be a Brede Hangeland type with stats like 424 headed clearances topping the league. Fulham conceded just 10 set piece goals, the fewest in the league. That 13 goal difference could have been the difference between 4th place and the title. Therein lies the solution.