However it was all to play for at the break as Scarlets top try scorer this season Andy Fenby crossed again to lead his side into the break just 11-5 down.
However 21 unanswered points from Leinster in the second half settled the contest, last year's runners-up running out 32-5 winners.
And while admitting that his side were their own worst enemies, Easterby simply hopes he won't have to rue the Scarlets' second-half showing further down the line after defeat means they slip out of the RaboDirect PRO12 play-off places.
"It's a disappointing result for us given the hard work the boys put in; but our ill-discipline and individual errors cost us heavily and in the second half we didn't help ourselves as we fed them too many opportunities," he said.
"I wasn't happy with how we finished that game to give away two tries when we were at 18-5 and give them the bonus point - that could come back and bite us.
"Our accuracy had really improved in recent weeks so it was frustrating to see ourselves go backwards - but we'll come back stronger and more determined next week and won't be dwelling on this weekend's result too much.
"We'll work hard in the build-up to Friday against Edinburgh; we have to react to this immediately and get back some momentum and finish this block of rugby at the right level."