According to Matthew Dowd the following are true:
"Throughout 1983, former President Reagan was behind Walter Mondale by as many as nine points, and against possible opponent John Glenn, Reagan was behind by as much as 17 points in 1983. Even at the beginning of 1984, the polls showed the race between Reagan and Mondale was a statistical dead heat. Reagan won in a landslide carrying 49 states.
In 1987 and 1988, Vice President George Bush was behind in generic ballot polls by as many as 15 points, and against Michael Dukakis throughout 1988 Bush was behind by as many as 17 points. It was not until the Republican convention in late summer 1988 that Bush took a small solid lead. Bush went on to win by a fairly good margin in November.
In 1995 and early 1996, former Senator Robert Dole was often ahead of Clinton in ballot polling. The Wall Street Journal showed Dole with a two point lead in 1995. And Gallup had Dole with small leads in 1995 and January 1996 Dole had a three point lead over Clinton. "
Stop with the sky is falling garbage ....
It is not at all unusual for an incumbent to trail in polls the year before the election. In fact, it's typical.