Safe in the PL? What kind of f*cking achievement is that? So you get to go see how Arab and Russian crooks are spending other people's money, so what. Competing with the top teams in the PL is one thing, being one of the teams positioned 10-17th is more like a living death where you look over your shoulder every year. Far better to have a glorious cup run, a trophy in the cabinet, a commenorative DVD you can get out when you need cheering up, a run in Europe the year after, and it listed on your achievements, that your team was the FA Cup winner in year x, not some no-mark in the PL that was safe and tucked up in bed by game 35.
Definitely win the cup and go down. What's the point of even being in the PL if your only goal is to avoid relegation every year?
