Unreliable method, considering how is "volatile" such value, a single ping check is inaccurate. It's irrelevant to think it works fine on your server since it can't represent all servers. The method, as it is, doesn't make sense.
This is also redundant, there is are already others plugins which do a better job, like Lame Connection Punisher, where the approach would be more smart/accurate.
Unapproved.
New version. And just to let you know this is not yet a final! I will make changes as needed.