Philip Rivers' alarming dip in form during the 2019 season means his signing is no guarantee of success for the Indianapolis Colts, says Brian Baldinger.

The 38-year-old left the Los Angeles Chargers in free agency after 16 seasons with the franchise, agreeing a one-year, $25million contract at Lucas Oil Stadium.

Indianapolis hope eight-time Pro Bowler Rivers can provide them with a significant quarterback upgrade on last year's starter, Jacoby Brissett.

But former Colts offensive lineman Baldinger, now an analyst for NFL Network, believes the previous campaign, when Rivers threw for 23 touchdowns and 20 interceptions, is a cause for concern.

The Chargers missed the playoffs and went 5-11, just one year after Rivers had 32 TDs and 12 INTs as part of a 12-4 campaign in 2018.

Baldinger told Stats Perform: "He didn't play well last year, and it wasn’t because the offensive line was terrible, or because the defense started with Derwin James getting injured in preseason and all that.

"All that stuff is true, but they won 12 games the year before and a large part of that was because Philip Rivers was really good late in games. 

"Late against Kansas City, late against the Pittsburgh Steelers, late against the Baltimore Ravens in a playoff win, all this stuff was true. 

"But he didn't play well late in games last year, which is where your quarterback has got to elevate your team, he has got to put you on their shoulders. 

"You look at losses last year in Detroit, losses to the Oakland Raiders, losses to the Kansas City Chiefs, all late in games with interceptions by Philip Rivers. They were not good decisions.

"Is that just an outline of Philip Rivers, is that who he is? Because he didn't look good when you have to be good late in games. 

"I don't know what you're going to get, are you going to get 2018 Philip Rivers or 2019 Philip Rivers? I don't know yet and I don't think anybody knows."