Hibernian manager Lee Johnson questioned the mentality of his team and said he was "sick to death of the mediocrity" in front of goal after they were hammered Hearts.
Hibs have now won just two of their last 11 Scottish Premiership matches.
"There's no doubt mentally we've got to be stronger as a team," Johnson told BBC Scotland.
"I'm sick to death of the mediocrity in that final third. We lift everyone by getting into the final third, but the final action is the most important action.
"We're brave and bold when we're two goals down. You've got to be the best player on the pitch at 0-0."
A costly error from Manchester United loanee Will Fish led to the opening goal for Shankland, as Hibs threatened to unravel in a poor first-half performance.
Johnson's side did improve after the break, but still conceded a third in stoppage time, meaning they trail Hearts by nine points and are down in eighth.
Johnson added the first half was "sorry" as he bemoaned his side's end product.
"[At] Key moments in the game they delivered and we didn't. I think that is a little bit of the story at the moment at the club.
"It's a fantastic football club but we're not doing enough at the moment. I think that showed today in the first half."