In footballing terms the word bottler refers to a player who initially plays well but makes a huge mistake or lets the team down when it really matters. i.e missing a penalty, missing an easy chance, losing your temper and getting sent off.
You can also refer to football teams as bottlers. For example Aston Villa are well known as bottlers because they seem to always be in good form at the beginning of the season but towards the end they lose this form and end up missing out on Champions League football, despite looking like they could be the best side in the premiership at the beginning of the season.
Eugene Dadi is such a bottler, what an awful penalty that was.