I've been trying to come up with different ways to visually represent results. I like this one.
That both Benitez and Houllier were in charge for six seasons allows for a straightforward comparison, even if we don't count the first 12 games of 1998-99 because of the ill-fated Evans/Houllier managerial pairing. Houllier's win percentage was 50%, Benitez's 55%. Both finished 2nd once, 3rd twice, 4th once, 5th once, and 7th once.
I'd like to direct your attention to a couple of areas.
First, the lower portion of Houllier's – and, to a lesser extent, Benitez's – wheel. There's an argument for a winter break right there, especially the results from 2001-02 and 2002-03. From the 15th match of the season through the 23rd, 54 matches over Houllier's six years, Liverpool won just 19, losing 18 and drawing 17, a win percentage of 35% compared to Houllier's 50% overall. Benitez's record during the winter months is better, but there's still the greatest concentration of draws in that part, especially during the '08-09 campaign – draws which directly led to Liverpool failure to win the league.
However, both managers had an outstanding record during the run-in. Benitez's sides suffered just four losses in the last seven matches during his six campaigns: 28 wins, 10 draws, 4 losses – winning 67% of the matches, dropping just 32 of 126 points. And half of those losses came in 2006-07, when Liverpool used a weakened line-up in the league while focusing on the Champions League Final – something Neil Warnock still complains about.
Houllier's results during that frame weren't quite as impressive, especially in 1999-02 and 2003-04, but there are still far more wins than draws or losses from, say, nine o'clock to midnight. His record of 13 wins, 1 draw, and 1 loss to close out 2001-02 is what led to Liverpool's second place finish that season, spoiled by the clutch of losses and draws during the winter when Liverpool dropped from 1st to 5th. But then Liverpool went out and bought Diouf, Diao, and Cheyrou, finished 5th the next season, and the rest is history.
Here's hoping Brendan Rodgers lasts six seasons (at least), and can replicate some of the heights hit by either of these managers.