The west Wales region were edged out by Ulster in a error-strewn encounter in which Andrew Trimble’s interception try proved the ultimate difference.
Aled Thomas slotted four penalties to salvage a losing bonus-point but Easterby was bitterly disappointed with the result.
“There are no excuses,” said the Scarlets head coach. “They didn’t have everyone back and we were at home, coming off a good win over Munster.
“We lacked accuracy in certain areas and put ourselves under pressure.
“The bonus-point isn’t much of a consolation now but it might give us something at the end of the season when there are only a couple of points between positions.”
The Scarlets remain second in the RaboDirect PRO12 and their attention now turns to the Heineken Cup and their back-to-back clashes with Exeter Chiefs.
They welcome back their Wales contingent today but are set to be without George North, Josh Turnbull and Rob McCusker.
“We will try to get as many of the boys back into the squad as we can without changing too much,” said Easterby.
“We will still be missing some players but hopefully we can pick a strong squad for a game that we have to win.
“George is probably going to be a couple of weeks but we will know more today and tomorrow. Rob and Josh won’t be available, again we’re looking at a couple of weeks. There are a lot of players we are desperate to get back.”
But Easterby will have the likes of Matthew Rees, Tavis Knoyle, Rhys Priestland and Jon Davies back at his disposal for the clash.
And he was particularly impressed with the recent form of international newcomers Liam Williams and Aaron Shingler.
“I was impressed but not surprised,” said Easterby.
“They have gone really well for us, we have a lot of faith in them and they’ve shown some regional form in the national jersey.”
Easterby expects a similar challenge from the Chiefs as was posed by Ulster on the weekend but he insists his side must improve.
“The won’t be too dissimilar to Ulster,” added the former Ireland flanker.
“They have a good forward pack, they’re winning a lot of rugby and will come here with plenty of confidence.
“They’re a good team and we will have to be a lot better than we were on Sunday.”
