Hamburg are the only club to have remained in the top flight of German football since its inception 50 years ago, but they only just stayed their last season when they finished 15th.
They have already been knocked out of the DFB-Pokal in the first round to third-division opponents this time around, and started the Bundesliga season with a home defeat to Nurnberg, and Seeler says the alarm bells are already ringing.
"I am quite concerned because I cannot see any improvements at all," he said. "And that is what the director of sport is judged on.
"But all he keeps repeating is that the team is developing, and that somebody else is coming, then somebody else.
"When I hear that or read that, I just shake my head.
"We have players who are not good enough for the Bundesliga, it is as simple as that."
Seeler's words were aimed at the club's director of sport Frank Arnesen, who says he is working on bringing in new recruits, but apart from goalkeeper Rene Adler, defender Paul Scharner and striker Artem Rudnevs, has delivered little.
"We need a creative player who can move around the midfield, a poacher who can cause problems in the penalty area and somebody to stabilise the defence," added Seeler in the Die Welt newspaper.
"What I saw against Nurnberg was even worse than last season."