As the Jets and Giants begin their preseason schedules this weekend, both teams have one major unanswered question hanging over them. For the Giants, it’s whether Eli Manning and his receivers can turn last season’s moribund passing game around. For the Jets, it’s whether a defensive unit that has undergone some major personnel changes can grow into one of the best in the league.

Last season, the Giants, who open the preseason Saturday night at Cleveland, had former league MVP Kurt Warner to be Manning’s mentor. This year, they’re putting all their eggs in the Manning basket. Behind the second-year quarterback sit two players associated more with television than with football: Jesse Palmer, who had the lead role for a season of “The Bachelor,” and Tim Hasselbeck, whose wife Elisabeth is a co-host of “The View.”

This is Manning’s team, and early reports out of camp have said he’s struggling to establish any sort of chemistry or rhythm with his receivers. He’ll have to shake off that rust in a hurry, but in order to do so he needs all his weapons available. That hasn’t happened so far in camp, which helps to explain the reported lack of chemistry. Tight end Jeremy Shockey has missed practice time with a hamstring strain; Shockey’s backup, Visanthe Shiancoe, has a bad knee; and wide receivers Plaxico Burress and Jamaar Taylor have missed time with hip flexors.

Head coach Tom Coughlin announced yesterday that Manning will be on the field for 12 to 15 snaps against the Browns on Saturday. It’s not much, but it may be enough to discern whether any progress has been made in two weeks of training camp. Manning routinely looked tentative on the three-step drop last season, so his ability to pull the trigger on quick slants to Burress or Amani Toomer on Saturday may give some indication as to whether any progress has been made during the off-season.

The best news for the Giants might be that Coughlin’s teams have a history of adapting to his system in their second year. At Boston College, Coughlin went 4-7 in his first year in 1991 and 8-3-1 in his second; with the Jacksonville Jaguars, Coughlin went 4-12 in his first year in 1995 and 9-7 (plus two playoff wins) in his second.

Coughlin’s demanding style can breed resentment in the locker room at first, but usually yields results in the long run. If it’s going to work for him with the Giants, though, he’ll need Manning and the receivers to get on the same page.

Meanwhile, the Jets, who host the Detroit Lions tonight, made headlines when they signed free-agent cornerback Ty Law this week. The presence of Law can make a big difference in the secondary – if he’s healthy. He won’t play tonight, and there have been conflicting reports about just how fully he’s recovered from foot surgery in January. In 2003, Law was the best cornerback in football. But he was 29 and healthy then. He’s 31 and hobbled now.

At first glance, Law’s contract looks like a good deal for the Jets. But there’s a reason he was available: Other NFL teams aren’t convinced that the broken bone in his left foot is completely healed. When he worked out for the Lions, Law and his agents said he was ready to play, but the Lions showed considerably less enthusiasm. If he really had been fully healthy, perhaps Law would be on the opposite sideline tonight.

The Jets have issues elsewhere in their secondary, beginning with the absense of veteran Ray Mickens, who they released to make room for Law. Mickens, though too small at 5-foot-8 to stay with the bigger receivers, was usually dependable in sticking with quick receivers, especially on inside routes. That responsibility will now fall to sixth-year man David Barrett, who will start at corner opposite Law in the regular season.

While Law rests in the preseason, the Jets will likely insert rookie Justin Miller as a starter. Second-year free safety Erik Coleman played very well as a rookie, but there’ a glaring hole at strong safety. Oliver Celestin, a second-year player who has never started a game, is currently at the top of the depth chart.

The Jets drafted safeties Kerry Rhodes in the fourth round and Andre Maddox in the fifth round this year, and they had better hope one of them turns out to be as pleasant a second-day draft surprise as Coleman was in 2004. The coaching staff will be monitoring Miller, Celestin, Rhodes, and Maddox carefully, hoping that at least one of them proves ready to be an NFL starter.

Last year’s first-round pick, Jonathan Vilma, turned in an excellent rookie season and gives the Jets cause for optimism in 2005. But Vilma, a middle linebacker, was helped last season by two good defensive tackles in front of him. One of those tackles, Jason Ferguson, is now in Dallas; the other, Dewayne Robertson, has struggled through training camp with a gimpy knee.

Elsewhere on the defensive line, pass rushing specialist John Abraham has missed camp because of a contract dispute with the team. Abraham probably will sign the Jets’ one-year, $6.7 million contract offer some time before the season starts. Still, having a star player out of camp can’t be good for a defense with so many question marks.

Because of that uncertainty along the defensive line, the most important player to keep an eye on tonight might be nose tackle James Reed. He’s been a dependable – but not spectacular – backup for the last four years. At 286 pounds, he’s small for a defensive tackle, but Reed needs to be a big presence in the middle with Ferguson gone and Robertson hurting.

Preseason games don’t count in the standings, but that doesn’t render them meaningless. They’re the best tool available – both for the coaches and for the fans – of gauging how much talent a team has, and how well that talent fits together. This weekend, the Jets and the Giants will find out just how much work they have ahead of them.

Mr. Smith writes for the statistical Web site FootballOutsiders.com.