Moriyasu's extreme caution was perhaps justified against Germany but to keep the attacking talent at his disposal on the bench against a team that lost their tournament opener 7-0 looked like a waste bordering on the criminal.
The likes of Takumi Minamino and Kaoru Mitoma had shown what vim and vigour they could bring to the Japan attack against one of the best defences in the world after a raft of substitutions in the 2-1 win over Germany.
Although Moriyasu made five changes for the Costa Rica match in a squad rotation ahead of their final group match against Spain, only Ritsu Doan of the substitutes who came on to transform the Germany match was given a start.
Japan again began with a back four, as they had for the first hour against Germany, switching to the more adventurous three-man defence only at halftime.
The Samurai Blue looked clueless as they tried to break down a Costa Rica side determined to avoid further embarrassment and who kept 10 men behind the ball for much of the time.
Japan's players languidly stroked the ball around in front of the massed red shirts but never really looked like finding the pass that would allow their forwards a clear sight of goal.
Junya Ito and Mitoma finally got on to the pitch just after the hour mark to trigger a marginal improvement but it was not until Minamino joined the fray in the 82nd minute that Japan looked anything like dangerous up front.
By then, Japan, for all their dominance of possession and territory, were a goal down after a defensive error gave Keysher Fuller a glimpse on goal which he took with alacrity.
It was Costa Rica's first shot on goal in the entire match but that, ultimately, was more than Japan managed over the 90 minutes.
Moriyasu was unapologetic about his team's insipid display only a few days after one of their greatest victories.
"I have no regrets, to be honest," he told reporters.
"The result was a shame but doesn't mean that what we've done was wrong. I decided the tactics. So the result didn't work out but we tried.
"I believe this was what Japan needed in that endeavour."
