Iowa's Scherff, Donnal Display Why They're Top Offensive Tackle Duo at Pro Day

The Iowa Hawkeyes program developed into an assembly line of offensive line talent under the direction of head coach Kirk Ferentz. It's a pipeline of technically sound zone-blockers that will add two new members to the NFL during this year's draft. 

Since Ferentz took over the program in 1999, 13 of his offensive linemen have been drafted into the NFL. Only the Wisconsin Badgers and Miami Hurricanes have produced more draft picks at that position over the same amount of time. 

Ferentz, a former offensive line coach for the Baltimore Ravens and Cleveland Browns, knows how to develop the big boys up front. 

This year's offensive tackle tandem of Brandon Scherff and Andrew Donnal may even be the best twosome the coach placed into the professional ranks during the same draft year. 

Scherff is widely considered the best offensive line prospect in this year's class. His position has yet to be determined, though. Even if he's not selected as an NFL left tackle, Scherff is still considered a potential top-10 talent. 

Bob Sturm, who covers the NFL draft for the Dallas Morning News, was effusive in his praise of Scherff prior to the team's pro day Monday: 

When Sturm broke down the offensive tackle for the publication, he wrote:

"

I can’t swear he is a left tackle, but he is going to be a 'butt-kicker' at some position for the next 10 years, I am sure of that. He is versatile and he is smart. He is competitive, and he wants to bully your side. ... I think his floor is higher than just about any prospect in this draft, and while the ceiling may not be as high, if you are looking for 'bust proof' and getting a real solid starter as the absolute worse-case scenario, I think I would rubber stamp an investment in this player. He is very solid and could play any of 4 OL positions.

"

Sturm's analysis is consistent with many projections for the Iowa product. Scherff is often considered a guard prospect instead of a more valuable left tackle due to his lack of length at the position and stiffness in the hips.

Player	Gallery	Scherff
Height	6'7"	6'5"
Weight	323	319
Arm length	32.25"	33.375"
Bench press	24	23
40-yard dash	4.98	5.05
10-yard split	1.70	1.78
Vertical	30"	32"

The reigning Outland Trophy winner will undoubtedly be compared to Robert Gallery, who was the last member of the Hawkeyes to win the award. Gallery was selected with the second overall pick in the 2004 NFL draft by the Oakland Raiders, but he never found a home at left tackle despite a dominant collegiate career. However, the former top-five pick eventually transitioned to guard and put together a respectable eight-year career. 

Gallery was considered a physical marvel at the time. It didn't translate to the NFL ranks, though. 

Scherff's workouts at the NFL combine and Iowa's pro day were opportunities to prove he could stay on the blind side. 

Instead, the talented offensive tackle tweaked a hamstring while running his second 40-yard dash in Indianapolis. He didn't complete a full workout. 

Scherff was ready to go at Iowa's pro day and came away pleased with his overall effort, according to The Cedar Rapids Gazette's Marc Morehouse:  

"

Very upbeat group of players. Scherff is planning to go to Chicago for the draft. Everyone seemed happy with their numbers.

— marcmorehouse (@marcmorehouse) March 23, 2015"

One of the events Scherff didn't complete at the combine was the vertical jump. The offensive tackle posted a 32-inch leap Monday, per the HawkeyeReport.com's Tom Kakert. Scherff would have finished among the top five performers at his position with that effort. 

The number shouldn't catch anyone completely by surprise. Scherff's lower-body explosion was never in question. A 480-pound hang clean max clearly shows how strong the Iowa native really is. 

In fact, Scherff posted three reps of 443 pounds while doing hang cleans last July. 

This type of lower-body power and core strength can be used to dominate at the point of attack, but it only provides more ammunition to the argument that Scherff should slide inside to guard, where he can uproot bigger and more physical defensive tackles. 

The lineman put the entire discussion to rest by remaining noncommittal to a preferred position, via Morehouse: 

It shouldn't matter if Scherff projects to guard or even right tackle over left tackle. The blind side may hold more value, but the lineman owns All-Pro potential at the other positions. That by itself is worthy of a top-10 selection. 

Not only is Scherff generally considered the top offensive line prospect in this year's class, but Iowa also might have produced one of the class' most well-kept secrets. 

Reese Strickland-USA TODAY Sports

Donnal doesn't receive the attention of Scherff, but the Hawkeyes right tackle could potentially develop into a starter much like he did over the course of his Iowa career. 

"Smart, average athlete. Good power in the run game, but a little stiff," Bleacher Report's Matt Miller told 247Sports.com's Andrew Kulha when describing Donnal's game. 

Like most Iowa products, Donnal is viewed as a polished prospect. While an argument can be made that these players present less overall upside, NFL scouts view it in a positive light.

Defensive tackle Louis Trinca-Pasat told Morehouse after the pro day that teams don't necessarily see Iowa prospects as rookies when they enter the league: 

Donnal is no different.

The Ohio native worked his way into the starting lineup as a senior. Prior to the 2014 campaign, Donnal only started two games during his four years on campus. Both of those starts came at right guard. Yet he continued to work hard and eventually became the team's top right tackle. 

NFL Network's Ben Fennell even provided Donnal with tremendous compliments. Fennell noted how well the senior played last year, and his play even trumped his highly touted bookend at times: 

Donnal's improvement continued throughout the pre-draft process. 

At the combine, the right tackle measured in at 6'6" and weighed 313 pounds. He ran a 5.31-second 40-yard dash and leaped 32 inches in the vertical jump and 8'5" in the broad jump.

Donnal's biggest improvement, though, occurred in his overall strength. 

The offensive lineman only benched 225 pounds 17 times in Indianapolis. Donnal easily eclipsed that number in Iowa City, according to Morehouse: 

The bench press wasn't Donnal's only area of improvement. 

While a time wasn't provided, the offensive lineman apparently improved upon his 7.84-second three-cone combine time as well. 

Scouts will note Donnal's continued progression and see far more upside than an Iowa product is normally given. 

With a potential top-10 pick and mid-round selection at offensive tackle last season, the Hawkeyes owned college football's most talented pair of bookend protectors. That combination is difficult for Oklahoma's Daryl Williams and Tyrus Thompson, who are both considered mid-round prospects, to beat. Other teams have plenty of talent across the offensive line that will be featured in this year's class, yet no one can compete with Iowa's duo even if Scherff doesn't play left tackle at the next level. 

Ferentz will be tasked with replacing both, but he'll be OK. The coach has found a way to continually put quality offensive linemen on the field. 

Scherff and Donnal, meanwhile, will enter the league as arguably the most prepared blockers in this year's draft class. 

Brent Sobleski covers the NFL draft for Bleacher Report. Follow him on Twitter @brentsobleski.