Well Lewry isn't quite as unlucky as Martin Bicknell - Bicknell was churning-out fantastic figures game after game, season after season, rarely picking-up injuries, doing everything you could possibly ask of a bowler.
Lewry, on the other hand, was taking 9-90 one match and 2-190 the next. Looks impressive overall, but since people tend to look at individual games when assessing a player you can tell he's stupidly, and unspeakably frustratingly, inconsistent. Add to that he's always had injury-problems - not as bad as say a Richard Johnson or Mfuneko Ngam - but enough to keep him out of 3 or 4 games a season.
And he's, perhaps understandibly, not been picked very often for the one-day game. If you compare his record to Kirtley's you can see why Kirtley was the one always at the back of selectors' minds.