Another idea: if a new submission (but not older than some threshold, maybe 24h?) did not reach the front page, each up-vote resets the submission time. Now if

Another idea: if a new submission (but not older than some threshold, maybe 24h?) did not reach the front page, each up-vote resets the submission time. Now if a story is noticed and upvoted when it is already reaching the bottom of the 'new' category, it is unlikely that it will accumulate enough votes fast enough to reach the front page.