The Giants aren’t just winning; they’re dominating.

Yesterday’s 33–15 victory over the San Francisco 49ers was the Giants’ fifth straight win, and their fourth straight by more than 10 points. A garbage-time 49ers touchdown made the score look more presentable, but the Giants bullied the 49ers all day.

The Giants’ defensive line has led the way on this winning streak by exploiting the weakest link in the opposition’s offensive line. Yesterday was no different. Defensive end Michael Strahan thoroughly whipped 49ers rookie offensive tackle Joe Staley, finishing the game with 2.5 sacks and making life miserable for 49ers quarterback Trent Dilfer. Strahan wasn’t the only one who made Dilfer wish the injury to 49ers starter Alex Smith hadn’t forced him to give up his usual job holding a clipboard on the sidelines. Justin Tuck had 1.5 sacks and Osi Umenyiora had a sack and forced fumble that he picked up and ran 75 yards for a touchdown.

No one has benefited more from the defensive line’s ability to rush the passer than cornerback Sam Madison, an 11-year veteran who is playing his best football in years. On a second-quarter pass, Madison lined up as though he would hang back in coverage on the outside, but he knew that when Dilfer felt the Giants’ blitz, he would look in the direction of his slot receiver. Madison read the play perfectly and jumped in front of Dilfer’s pass for an interception.

The Giants’ other starting cornerback, rookie Aaron Ross, hasn’t learned all the tricks that Madison knows, but he continues to show why the Giants used a first-round draft pick on him. After getting beaten in coverage on Dilfer’s second-quarter touchdown pass to Arnaz Battle, Ross settled down and had a very good game, even coming on a blitz and sacking Dilfer in the fourth quarter.

Running back Brandon Jacobs had an outstanding day, finishing with 18 carries for 107 yards and often literally running over the 49ers. The Giants’ running backs and receivers broke tackles all day, starting with the first play, a pass to tight end Jeremy Shockey, who hurdled a defender to pick up a first down.

Eli Manning’s numbers were nothing special: 18-of-31 for 146 yards, with two touchdowns and one interception. His performance was better than the statistics indicate, though. The interception was more an unlucky bounce than a bad decision, as a deflected pass landed in the hands of 49ers linebacker Derek Smith. And Manning’s receivers dropped several passes, starting with the first possession, on which running back Derrick Ward dropped two balls (Manning’s only two incompletions on an outstanding drive), the second of which should have gone for an easy touchdown. Manning showed total control of the offense on that opening possession, twice using his cadence to draw the 49ers offside. The first drive ended with an Amani Toomer touchdown that made him the team’s all-time leader in touchdown catches.

Lawrence Tynes missed the extra point after Toomer’s touchdown, and that points to the Giants’ biggest weakness: special teams. Even when he makes his kicks, Tynes’s field goal attempts often look wobbly and barely sneak inside the uprights, and his kickoffs are too short. It’s probably time for the Giants to bring in another kicker. The Giants also had a punt blocked, resulting in a safety.

The Giants’ other major problem is the one that has gnawed at coach Tom Coughlin as long as he’s been in New York: They still make too many stupid mistakes. Few coaches preach the importance of avoiding penalties as vociferously as Coughlin, but more often than not, the Giants’ performance on the field fails to match his rhetoric. Yesterday, linebacker Antonio Pierce was the biggest culprit, twice getting called for personal fouls against Dilfer, both of them negating big plays by the defense. Overall, the Giants were flagged for 10 penalties and the 49ers accepted eight of them, resulting in 67 yards and three first downs.

Those mistakes show why any excitement about the Giants’ 5–2 record may be premature, especially considering that they still have beaten only one good team, the Washington Redskins, at the beginning of this five-game streak. But even against an easy schedule, no one expected the Giants to be what they’ve been the last four weeks: Dominant.

Mr. Smith is a writer for FootballOutsiders.com.