WHAT I LEARNED FROM THURSDAY'S 12 PRESEASON GAMES

Week 1 of the preseason is underway with 12 matchups taking place Thursday night. Browns quarterback Baker Mayfield and Giants running back Saquon Barkley were among several rookies who made their debut. Both stole the show and were the talk of the night.

HERE'S WHAT I LEARNED ON THURSDAY NIGHT

STEELERS 31, EAGLES 14

The Eagles spent their offseason stacking an already loaded defense, adding Michael Bennett and Haloti Ngata to the front seven. The first quarter of Philadelphia's preseason opener proved the defense hasn't lost the slightest step. Fletcher Cox, starting alongside Bennett and Chris Long, ripped through Pittsburgh's first-team offensive line on his first series, recording a sack and a tackle running down a screen. Malcolm Jenkins and Nigel Bradham split a sack of their own on the next series. One game in, the investment into Jim Schwartz's unit already looks well worth it, even if their competition on Thursday was Landry Jones and James Conner. One potentially concerning development: Sidney Jones took a hard hit to his lower leg and was looked at by trainers. The cornerback missed most of his rookie season with an ruptured Achilles, but said after the game he suffered only a minor lower leg injury. That's the risk you take playing your starters more than two series in the preseason opener.

49ERS 24, COWBOYS 21

These were the words on Tuesday from Cowboys slot man Cole Beasley. The jury's still out on that proclamation, but third-round rookie Michael Gallup looked saucy grabbing a pristine, 30-yard touchdown lob from quarterback Dak Prescott. That marked the biggest on-field moment from any of the starters on a night that saw Ezekiel Elliott watch from afar and San Francisco wonder boy Jimmy Garoppolo hit the bricks after one scoreless series.

The Niners, meanwhile, are ready to wave farewell to preseason after running back Matt Breida(shoulder), defensive tackle Solomon Thomas (head), linebacker Malcolm Smith (hamstring) and offensive tackle Garry Gilliam all left the field.

BUCCANEERS 26, DOLPHINS 24

Ryan Tannehill's first in-game action in nearly 20 months was a rather subdued affair, but he showed no signs of his surgically repaired knee being an issue for him this season. Tannehill connected on 4 of 6 passes for 32 in his one game-starting series against the Buccaneers. His movement in the pocket looked very fluid and comfortable -- a mirror image of what he's looked like in training camp. Ultimately, Tannehill couldn't punch the Dolphins into the end zone, but his solid execution in the offense is a positive sign for a Miami squad eager to put last year's disappointing season behind them.

PANTHERS 28, BILLS 23

Rookie D.J. Moore is putting veteran receivers Torrey Smith and Jarius Wright on notice. The Panthers' first-round pick led the team with 75 yards on four receptions, working with backup quarterback candidates Taylor Heinicke and Garrett Gilbert. The highlight was a third-down conversion in which Moore offered shades of former Vikings star Percy Harvin with extraordinary stop-and-start suddenness to slip one tackle and break another for a first down that set up C.J. Anderson's 4-yard score.

BROWNS 20, GIANTS 10

Giants rookie back Saquon Barkley made his presence felt right away with a tantalizing 39-yard gain on the game's opening snap. The second overall pick in the draft scanned the line, cut to his right, spun around Browns defensive lineman Emmanuel Ogbah and showed his speed blasting up field for a big chunk of real estate. He's just what the doctor ordered for a Giants ground game long lost at sea.

Baker Mayfield, though, would not be outdone, taking over in the second quarter and guiding the Browns to a pair of scores. The first -- a 14-play, 72-yard march -- saw the No. 1 overall pick unfurl a key third-down completion before pegging David Njoku for a 10-yard touchdown. Mayfield later found fourth-round wideout Antonio Callaway for a 54-yard score. Mayfield (11-of-20 passing for 212 yards) capably rolled through his progressions, showed timely mobility and looked the part. It's worth noting he took the field after starter Tyrod Taylor ripped through the G-Men, going 5-for-5 passing for 99 yards with another touchdown strike to Njoku.

COLTS 19, SEAHAWKS 17

Perhaps Seattle's rebuild on defense is truly, as Pete Carroll described it this summer, a reload. After losing Michael Bennett, Richard Sherman, Kam Chancellor and potentially Earl Thomas in the offseason, the Seahawks saw three newcomers step up in the front seven on Thursday night. Rookie linebacker Shaquem Griffin led Seattle with nine tackles, including one for loss; first-year defensive end Rasheem Green frustrated Indy with seven tackles and 1.5 sacks; and former Colts defensive end Barkevious Mingo also tallied a sack. On the other side of the ball, Chris Carson (6.5 YPA) far outplayed rookie Rashaad Penny (2.0 YPA) in the backfield.

BENGALS 30, BEARS 27

Second-year speed demon John Ross was a big factor in the Bengals' first half, playing alongside A.J. Green and Tyler Boyd as the No. 3 receiver. After slipping and falling to contribute to Kyle Fuller's pick-six, Ross came back strong the next drive with a red-zone catch-and-run to set up Boyd's touchdown. He nearly hauled in a score of his own just before halftime but couldn't get his second foot down on a leaping attempt in the back of the end zone.

SAINTS 24, JAGUARS 20

What little we saw from Blake Bortles was promising. The Jaguars quarterback emerged from an offseason of questions to author an opening scoring drive that saw Jacksonville weave through the Saints for 79 yards off 15 plays before Bortles danced in for a two-yard touchdown. The Jaguars starter was 6-for-9 passing on the march for 53 yards with a well-timed 16-yard completion to Dede Westbrook on 3rd-and-10. As for the Saints, Drew Brees sat in the shadows while Tom Savage took opening snaps and Mr. Everything Alvin Kamara totaled 18 yards on four touches. Rough-and-tumble Mark Ingram ran for another 23 yards of his own.

PATRIOTS 26, REDSKINS 17

If you like running backs, then this preseason opener was for you. New England handed the ball off again and again to Jeremy Hill (51 yards, TD) and Mike Gillislee (43 yards), who split carries almost evenly on the night. Down the depth chart, UDFA Ralph Webb (46 yards) scored two touchdowns and two two-point conversions while rookie Sony Michel (knee) and Rex Burkhead (undisclosed injury) sat out. Jobs are on the line in New England's crowded RB room, but neither Hill nor Gillislee did anything special to secure his roster spot. Washington played most of its backs, save for the injured Chris Thompson. Rookie Derrius Guice (six carries for 19 yards) was impressive in spurts, but left the game early with a knee injury; he'll get an MRI on Friday. A non-RB note: Special-teams savant Cordarrelle Patterson is going to be a factor in New England's passing game (two catches for 38 yards Thursday).

PACKERS 31, TITANS 17

Who's going to be Aaron Rodgers' backup in 2018? Brett Hundley and DeShone Kizer didn't provide a definitive answer to that question. Hundley, the incumbent, got the start and fared slightly better, completing 9 of 18 passes for a 108 yards and a touchdown. While he looked fairly solid, he also had an interception that brought flashbacks of his ho-hum performances from last year. Kizer, making his Packers' debut, connected on 9 of 14 passes for 134 yards.

RAVENS 33, RAMS 7

Lamar Jackson's second preseason game looked a whole lot like his first, save for two highlights sure to go viral. Jackson came in after one stirring series of Joe Flacco on Thursday night, and the rookie led Baltimore on a five-play touchdown drive, so far the highlight of Jackson's professional career. The first-year QB showed great touch on a 36-yard completion down the seam to Chris Moore to get Baltimore inside the red zone. Three plays later, Jackson broke two pairs of ankles on a nine-yard touchdown scramble, a run ripped from his Heisman reel. It was tough sledding after that first drive for Jackson though as the QB continued to struggle with short-field and downfield accuracy and pocket awareness. Final stats: 8 series, 7/18, 119 yds, 21 rushing, 1 total TD, 2 sacks. This is still Flacco's job.

TEXANS 17, CHIEFS 10

The matchup between two tantalizing quarterbacks taken in the first round of the 2017 draft fizzled out early in the first quarter of Thursday's preseason debut between the Texans and Chiefs. Returning from ACL surgery, Deshaun Watson completed his lone pass attempt for four yards before giving way to Brandon Weeden on the second possession. Patrick Mahomes' two drives fared no better, each resulting in punts. Expect to see more playing time for both QBs next week.