I'm sure Martin's biggest fans would make the counter-argument that he motivated a poor squad who couldn't win a game for months to put in a great late season run and almost sneak into the playoffs.
It's useful to look at how his Southampton team have done this season for comparison. Although they sold a load of players in the summer, they retained a good number of PL proven players and recruited plenty more with PL experience or quality Championship players. Most people would have had them as strong favourites to be promoted this season.
They opened with 3 wins and a draw, then lost the next 4 games. They then went on a very impressive 22 game unbeaten run and climbed to 2nd. At this point, they looked likely to go up automatically. They then lost 3 of the next 4, rallied to only lose 1 in 8, but are now on a run of 3 losses in a row.
So patches of great form, mixed with runs where they can't win a game. Pretty much a carbon copy of Russ' time here, except the great runs last longer and the poor runs end quicker. Which would be expected when he has a much better team. At some point, even his biggest fans have to acknowledge the pattern.