With the Chiefs set to visit Chicago on Thursday night, we’re in store for the annual mirage known as the preseason. Except that it isn’t always a mirage.

Pre-season games tell us more about a team’s prospects than do training camp drills, which tell us more than do off-season workouts. But that isn’t saying a whole lot for the significance of pre-season games because the starters are usually gone by the fourth quarter and coaches try to strike a balance between taking a good look at new players and trying to win.

What we’re watching in August usually isn’t a true measure of a team’s ability. The Chiefs, however, were an exception to that rule last summer.

When they lost all four pre-season games, scored just two offensive touchdowns and totaled a league-low 32 points, it was hard to dismiss that malaise as meaningless. True, Larry Johnson didn’t play except for three carries in the last game, a 10-3 loss to the Rams. And true, Herm Edwards used that game to reward quarterback Jeff Terrell for serving as an extra arm all summer.

Still, the overall outlook seemed bleak. And it was.

If a team is coming off a big season and hasn’t lost much talent, a poor preseason is nothing to sweat over. But if a team is coming off a losing season and shows few signs of life in August, another losing season is probably in the cards.

It’s a given that the Chiefs will perform better this preseason than last. Pre-season records are products of a team’s priorities. Edwards last summer gave his youngsters a good look and gave his veterans just enough playing time to keep the rust off. He wasn’t preoccupied with winning.

That was a sensible approach for a team coming off a playoff season. But now the Chiefs need an approach for a team riding a nine-game losing streak.

Edwards has made it clear that this summer, his starters will stay in longer and units, especially the offensive line, will remain intact. Given the need to build the confidence of a young team coming off a 4-12 season, he’ll make winning a priority.

Though most of what happens in the preseason usually stays in the preseason, there are some impressions about any NFL team that should be confirmed in September.

Speed and quickness are not illusions. Young players inevitably are surprised by how fast-moving the games become in the regular season, and it’s worth noting which players already are picking up the pace in August. Linebackers who cover a lot of ground, receivers who keep getting open and kick returners with a lot of wiggle, for instance, are good bets to keep contributing when the games start to count.

Starting quarterbacks should step up in August. Though the offenses may not yet be well synchronized and low-scoring goes are common, defenses are in a vanilla mode, especially in the first few pre-season games.

A passer sees few blitzes and shouldn’t be rushed into poor decisions. He should complete a high percentage of his passes.

That’s why the Chiefs’ staff had to be alarmed last summer when Croyle, groomed to be the starter, threw almost-unthinkable interceptions in each of the first three games. Clearly, he wasn’t ready to start in the NFL, and veteran Damon Huard took over for the opener.

The year before, it came as an unpleasant surprise that Chiefs quarterback Casey Printers’ three seasons in Canada hadn’t prepared him for the NFL. He seemed totally out of his element in his first pre-season game, and that was pretty much the story of his stint with the Chiefs.

A brilliant preseason for Croyle would not guarantee that he’s arrived. But you don’t want to see much inconsistency from a quarterback with six professional starts under his belt.

And you don’t want to see another winless preseason from a team that’s trying to win.