Wales centre Davies played 40 minutes as he ended a near three-month spell out with a pectoral problem but he was powerless to prevent the Exiles running out 29-10 winners in Reading.
The Scarlets shipped five tries in a game that was a dead rubber even before the weekend began after Saracens and Northampton had sewn up semi-final spots in the teams’ respective pools with a game to spare.
Victory would have given Simon Easterby’s side some welcome momentum to take back into the PRO12 run-in but a late George Earle try, a Gareth Owen conversion and a penalty from Josh Lewis was all they had to show for their efforts up the M4.
Former Scarlets wing Andrew Fenby ensured his old side got off to the worst possible start when he touched down after just four minutes and things got even worse for the visitors as an experienced Irish outfit had the bonus point sewn up before the break.
Shane Geraghty, Jamie Hagan and Sailosi Tagicakibau all crossed to leave the Scarlets with a mountain to climb at 22-3 down after the first 40 minutes but they were much better after the restart and drew the second period 7-7 as a result.
Earle powered over 10 minutes from time, with Owens’ conversion making it a 12-point ball game, but it was too little too late to affect the outcome and it was the home side who had the final say when Myles Dorrian scored their fifth try late on.
