TAMPA — From his vantage point in the coaches' box last season, Mike Smith could see the whole thing clearly. And that was the problem.

The Bucs' defense was bad for many reasons, the biggest being it did not have many good players, especially on the defensive line.

Smith, the defensive coordinator, will never say that. He doesn't have to.

The Bucs proved it by using big resources in the offseason on the trade for Jason Pierre-Paul, signing Beau Allen, Vinny Curry, Mitch Unrein and using the 12th overall pick in the draft on Vita Vea, who limped off the field during Sunday's practice with a left calf strain that the team does not believe is too serious.

The only constant has been Gerald McCoy. No matter how poorly the Bucs defense played, you knew two things about McCoy: he was going to perform well and he was going to be back on the team the next year.

God help him.

The Bucs were last in the NFL in total defense and sacks in 2017, and went from first to worst in third-down defense.

Putting pressure on the quarterback is the name of the game in the NFL. So naturally, everyone is focused on sacks. But sacks don't happen unless you can do the job against the run on the early downs.

"You know, everybody sometimes gets fixated on sacks and putting pressure on the quarterback,'' Smith said. "But the number one tenet in the game of football is stopping the run. If you can't get there and have an advantage with the sticks on third down, it's much harder to rush the passer.''

So for all the pass-rushing talent the Bucs believe they have acquired, it's how the Bucs play the run which will determine whether they win many games this season.

Pierre-Paul plays the premier pass rush position at right defensive end, but his ability to set the edge and disrupt the run could prove to be his biggest contribution.

"When we played them last year, just from our standpoint, we probably feared him more in the running game than we did in the pass game,'' coach Dirk Koetter said of Pierre-Paul. "That's not a threat. That's not a downgrade to him because we see good pass rushers every week, but a lot of those speed rushers can't play the run. I mean, he's 280 pounds.

"He anchors, he sets the edge, his length, he's hard to get into his body. He's got those long arms, and then he's so powerful. I was just watching a clip today on a big play where the tight end slices back across the line, they were playing the (Los Angeles) Rams last year. He just picked the tight end up and walked him right back into the ball carrier.''

Since his days as the defensive coordinator in Jacksonville where he had John Henderson (6 feet 7, 335 pounds) and Marcus Stroud (6 feet 6, 310 pounds), Smith has preferred big-bodied players inside to occupy blockers and free up his linebackers.

Smith has them now. Vea (6-4, 347) and Allen (6-3, 327) have joined Stevie Tu'ikolovatu (6-1, 340) to play alongside McCoy.

"Absolutely. You want your defensive linemen to be able to take up blocks and allow your linebackers to run free and you want to try to get as much resources as the offense can put on the four down linemen and that will keep the other guys free,'' Smith said.

In 2016, opponents converted only 32.5 percent on third down, tops in the league. Last season, 2016, the Bucs allowed an NFL-worst 48.1 percent conversions.

"We went from one to 32nd in third downs, and it wasn't because of what we did on third down,'' Smith said. "It's what we did on first and second down. We weren't very efficient on first and second downs. They had third and manageables and when you're in third and manageables, it's tough to defend.''

In 2016, opponents faced an average third down of 7.1 yards and produced 5.1 yards per play. Last season, the average third down was 6.88 yards but the Bucs defense allowed 7.1 yards.

The Bucs had 18 sacks on third down in 2016. Last season they produced only 11.

In the end, it gets back to players. Look at it this way, defensive end Robert Ayers (two sacks in 12 games) and defensive tackle Sealver Siliga (no sacks in eight games) are out of football. Defensive end Ryan Russell (two sacks in 14 games) just signed with Buffalo. Clinton McDonald (five sacks) took a pay cut after he failed a physical to remain with the Broncos.

That doesn't even count two other mainstays, safety T.J. Ward and cornerback Robert McClain, who are looking for jobs.

On paper, the Bucs are bigger and better. If they can stop the run, opposing quarterbacks could have some long days. At least, that's the plan.