In No. 25 Michigan State's 40-31 win over Indiana Saturday evening, it was that group that looked more vulnerable than it had been during MSU's first four games.

Indiana had executed its offensive game plan — almost — to perfection, and turned an impenetrable force into a piece of swiss cheese.

Behind the arm of redshirt freshman quarterback Michael Penix Jr. and the hands of wideout Whop Philyor, the Hoosiers gained over 350 yards of offense, the most an opponent has mustered against MSU's defense this season.

“They sort of out-formationed us I felt. They did formations that put us on the edge and put us out of, maybe, a lot of bubble passes, and we’re going to see those things so we’re going to have to work on those things," Michigan State coach Mark Dantonio said following the Spartans' win.

“I don’t think we’ve had a game like that defensively in a while.” 

The Hoosiers used their speed on the perimeter to their advantage, attacking the Spartan defense with quick-screens, dump-offs and then catching the secondary napping for downfield throws.

Penix finished 33-for-42 for 286 yards and three touchdowns. His yardage total was over 300 before the final play where MSU safety Michael Dowell returned a fumble for a touchdown when the Hoosiers began to lateral the ball across the field.

But, before that last-second debacle, Penix looked like a three-year starter, and not a freshman making his third career start and just coming back into the fold after missing the last two games with an injury.

With MSU leading 7-0, Penix connected with a wide-open Philyor when he got lost down the sideline from a miscommunication between defensive backs Josiah Scott and Xavier Henderson. Penix tied the game at 14 when he sauntered into the end zone from two yards out.

Then, Penix gave the Hoosiers their first lead of the game when he connected with Donavan Hale for a 12-yard touchdown to put IU up 24-21.

At one point, Penix completed 20 consecutive passes to set an Indiana football program record.

MSU's defense did come up with two important stops late in the fourth quarter to force IU punts. But, Penix was given the chance to tie the game again — and he took advantage.

With 2 minutes left in the game, Penix found Philyor again for an 11-yard touchdown to tie the game at 31.

Philyor caught a team-high 14 passes for 142 yards.

“They just spread the ball out," senior linebacker Joe Bachie said. "They were figuring out when we were blitzing and they were checking to the sidelines a bunch. When they saw us in a zone pressure, they were throwing the bubbles out there, throwing jailbreaks, they head some bubble-go’s off us, so they were making big plays and we couldn’t really stop that momentum they had for most of the game."

"For our standards, that wasn’t good at all for us.”

Michigan State's defense has been challenged this year. Western Michigan utilized slants and the middle of the field to gain 352 yards against the Spartan defense. Arizona State drove down the field without any hesitation to take a 10-7 lead with less than a minute to go.

But nothing like Saturday evening — not the way Indiana carved through MSU's defense. Not for a sustainable 40-plus minutes of gameplay.

When asked if he thought there was anything that MSU defense did — or did not do — against the Hoosiers, senior linebacker Joe Bachie didn't think so, nothing major at least. With a daunting three-game stretch against some of the top teams in the Big Ten, starting with a trip to Columbus next weekend to take on No. 5 Ohio State (7:30 p.m., ABC), there may be some concern. But, leaders on MSU's defense expect to get things cleaned up before then.

“I definitely think it will make us focus in a little bit more," senior safety David Dowell said. "Just because Indiana tested us, so thats going to make us focus in a little bit more, and I think will ultimately make us better for those games coming up.” 

After four weeks of dominance, it was shocking and rather eye-opening to see an offense go down the field without much resistance against MSU's defense.

But the Spartans aren't looking at it that way. A sign of struggle shows that there is still a lot of room for improvement within the defensive unit. And with a date against the Buckeyes looming MSU's defense will have to do just that.

“It's good to see us struggle a little bit, I guess, and our offense to pick us up," Bachie said. "Defense, will be on our stuff next week, we’re going to get this stuff figured out.”