Iowa fans hoping to see a quick response after last week's disappointing 20-19 loss to in-state rival Iowa State didn't get that today. The Hawkeyes were tied 0-0 with Troy after the first quarter and trailed 14-10 at halftime after conceding a pair of uncharacteristic big plays to the Trojans in the second quarter.

The second half provided a more emphatic response from the Hawkeyes, though, as they outscored the Trojans 28-7 after the break to roll to a 38-21 victory and improve to 2-1. Four Downs breaks down the major takeaways from the win.

It's been clear since the opener that Kaleb Johnson was Iowa's best weapon on offense and subsequent weeks have only emphasized that point. After going off for 187 yards and a pair of touchdowns against the Cyclones last week, Johnson went through, around, and over Troy's defense for 173 yards and two touchdowns on 25 carries.

His 39-yard run in the first quarter was the first real spark of the game for Iowa's offense, though the ensuing drive ended in a failed fourth-down conversion. There were no such failures on Iowa's next drive, which Johnson finished off with a short touchdown run.

Johnson gained another 20 yards on the ground on Iowa's next drive, which ended up stalling out and leading to a 42-yard Drew Stevens field goal. He finished the first half with 17 carries for 100 yards and one score.

The pounding that Johnson (and Kamari Moulton, who had two carries for 34 yards in the first half) put on Troy's defense in the opening 30 minutes paid dividends in the final 30 minute, with 155 yards and a pair of touchdowns on 24 carries (6.5 yards per carry).

Johnson got help -- Jaziun Patterson in particular was strong at the end of the game and finished with 72 yards and a touchdown on eight carries -- but he put on a show himself, with 73 yards and a touchdown on eight second-half rushes. The touchdown was particularly impressive:

Johnson's start to the season is the best Iowa has seen from a running back since Shonn Greene stopped moving furniture and started shredding defenses in 2008. Greene famously ran for 100+ yards in every game that season en route to a program-record 1,850 yards and eventual Doak Walker Trophy as the nation's best running back. Johnson has a long way to go to equal that overall season -- but he's off to a tremendous start.

In fact, in terms of raw numbers, Johnson is off to the best start by an Iowa running back in 27 years, since Tavian Banks demolished defenses in 1997.

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There were a lot of positives for the Iowa defense in Saturday's win. The maligned pass rush made its presence felt today, especially in the second half. Overall, Iowa's defensive line finished with four sacks, seven tackles for loss, and two additional quarterback hurries.

Ethan Hurkett was a terror at defensive end, with four tackles, two sacks, and two forced fumbles from one end position. Brian Allen and Max Llewellyn made an impact at end as well, with Allen notching a sack and a team-high 2.5 tackles for loss and Llewellyn getting a sack and a hurry. Yahya Black also finished with 1.5 tackles for loss in the game. This was a statement performance from the defensive line, although the "it was Troy" caveats also apply -- the line will need to show the ability to get pressure like this against Big Ten opponents as well.

Iowa also forced a turnover and recorded it first defensive score of the year, courtesy of this pick-six from Jermari Harris. Harris read the play perfectly and got some nice blocking on his way to the end zone to give Iowa a pick-six for a 17th straight season.

Overall, Troy gained 150 yards on two explosive touchdown drives (more on them in a moment) and 83 yards -- combined -- on nine other drives in the game. The defense didn't allow long, sustained drives from the Trojans and was able to force several negative plays.

The Harris pick-six was a high point for the secondary, but there were a few definite low points as well. Troy WR Devonte Ross twice got behind TJ Hall for big play touchdowns, first for 63 yards in the first half and then again for 62 yards in the second half.

Those big play breakdowns come on the heels of the long touchdown that Iowa conceded to Iowa State last week; that's three big play touchdowns allowed on defense in two games. For comparison, Iowa gave up just two plays of 60+ yards in 14 games last season.

Preventing big plays is one of the key tenets of Phil Parker's defense so the weakness the secondary has shown in that regard over the last two games is definitely a red flag, particularly with Big Ten play looming (and a game with Ohio State and the Buckeyes' fleet of explosive wideouts looming in just three weeks).

The Iowa defense wasn't the only unit vulnerable to big plays, either. In addition to Ross' two 60+ yard touchdown grabs, he also had a 77-yard punt return score in the second quarter.

The punt return was set up by a poor punt from Rhys Dakin -- the kick was a low line drive, easily returnable -- and some uncharacteristically poor defending by Iowa's coverage unit. They failed to seal the edge and once Ross hit the corner, he was gone, gliding down the Kinnick Stadium turf for a long touchdown.

The good news is that Dakin's subsequent punts were much better -- he had a 52-yard bomb that was inches away from being downed inside the 10-yard line and a 50-yard rocket with good hang time that was fair caught. The punt return touchdown seems a little flukier than the big pass plays that the defense allowed. Still, allowing big plays on defense and special teams dramatically reduces the margin of error for a team like Iowa, so Iowa's ability to prevent plays like that in future games this season will be something to watch.

Is the quarterback situation any clearer for the Hawkeyes three weeks into the season? Yes and no. Cade McNamara is still the unquestioned number one option for the offense -- at least between the 20s. McNamara took the vast majority of the snaps in the game and finished with generally solid numbers:

19-of-23 (83%), 176 yards, 0 TD, 0 INT, 146.9 QB rating

But McNamara also got sent to the sidelines on a few occasions when Iowa got inside the red zone. Brendan Sullivan entered the game at QB on a pair of goal-to-go drives -- and directed Iowa to two touchdowns. "Directed" is doing some heavy lifting there, of course, given that his contributions amounted to handing off to Kaleb Johnson on his four-yard score and this short shovel pass to Addison Ostrenga for a touchdown in the third quarter.

It's hard to say if Sullivan would have gotten more red zone work if Iowa had more opportunities because those opportunities didn't arise -- the Hawkeyes' other three touchdowns came on Harris' pick-six and 30+ yard runs by Johnson and Jaziun Patterson. Sullivan also got reps with the second-string offense at the end of the game, though he attempted no passes on those plays.

Again, McNamara wasn't bad in the game -- an 83% completion rate is pretty uncharted territory for an Iowa quarterback in recent years, he successfully avoided turnovers and was generally efficient. He did take a few drive-killing sacks, although poor pass protection was a factor on those plays as well.

But nearly all of the big play juice from the offense came from the running game; the passing game had one play over 20 yards (a 33-yard catch-and-run by Kaden Wetjen) on the day.

Jacob Gill was a reliable target and finished with 44 yards on five receptions. Luke Lachey also made his first catches since the season opener, finishing with three grabs for 25 yards. Kaleb Brown and Jarriett Bouie picked up their first receptions of the season as well, but Iowa still continues to struggle to get playmakers involved at the receiver position.