IMHO, and after decades of following the division, the team W-L records simply do not matter. Before the Wild Card, several times an NL West team did not make the playoffs and had a better record than teams from other divisons which did.
These NL West teams fight each other tooth and nail at least 12 times each. That means there are going to be more losses in the long run. Look at last year for example. The red hot Dodgers finish out the year by winning the NL West then the Giants took it all in the World Series.
In each of the previous 15 World Series NL West teams have been there 6 times, winning it all, 4 times. In the NLCS, the team to beat was an NL West team 10 times. In the NLDS, the team to beat was a NL West team 20 times.
Overall, the top three NL teams, NL West teams break down like this in total appearances in the World Series:
San Francisco/NY Giants- 20 2nd most; 1st in the NL
Los Angeles/Brooklyn Dodgers- 18 4th most; 3rd in the NL
In total WS wins by NL teams, San Francisco (8) is 2nd only behind the the Cardinals (11). The Dodgers (6) are 3rd.
By any measurement, the NL WEST is very competitive and pretty darn successful. Hence, IMHO,the most competitive, top to bottom, every year.