Ahh, the old clutch hitting canard! Love that challenge!
Will Clark overall career slash line: .303/.384/.497 for a career OPS of .880, or an OPS+ of 137. Great player.
Will Clark career "late and close" slash line: .288/.383/.478, for a tOPS of 96, or slightly worse than his overall production. He also had only 5 seasons where he outperformed his overall season OPS in "late and close" situations, against 10 seasons where he underperformed in those situations.
tOPS when ahead: 103
tOPS when behind: 95
tOPS in "high-leverage" situations: 108
Taken together, it means Will Clark, if anything, performed slightly better than usual in higher leverage situations (situation with higher outs, later in the game, with more runners on base) when his team was already ahead.
He was a tough guy and a great hitter, but not any more of a clutch hitter than our imperfect memories make him out to be.