Jon Giesler was a 6'5" offensive lineman for the Michigan Wolverines. In high school, he won the Ohio Class "A" State Championship in both shot put and discus. Miami chose him with their first round selection of the 1979 NFL Entry Draft with the 24th overall pick.
Giesler appeared in all 16 games as a rookie in 1979, and wore the number 79 throughout his Dolphins career. He appeared in all 16 games as Miami won the AFC East title with a 10-6 record. The only offensive category the Dolphins appeared in the NFL's top five was first downs by penalty, with 31 - a rather dubious distinction.
In 1980, Giesler moved to the starting lineup as the left tackle, a position he would hold for the rest of his NFL career. He started 10 games, nursing an injury during the other six. Miami finished the season with an 8-8 record, out of serious postseason consideration (All five AFC playoff contenders finished with identical 11-5 records).
1981 would see Giesler start all 16 games for the first time in his career, as Miami finished with an 11-4-1 record. The Dolphins won the AFC East before participating in one of the best games ever, a 41-38 overtime loss to the San Diego Chargers in the Divisional Playoff round.
In 1982, the Dolphins finished the season 7-2, as weeks three through nine were cancelled by the players' strike. Giesler started all nine games for Miami as the team cruised through the regular season. In the expanded 16-team postseason field, Miami won each of the three rounds by a combined score of 76-26 for an eventual berth in Super Bowl XVII. Miami's rushing attack led the NFL with 333 carries for an NFL third best 1,344 yards, while allowing an NFL low 11 sacks.
1983 would see Giesler again start all 16 games for Miami, as the team easily won the AFC East with a 12-4 record (the New England Patriots and the Buffalo Bills would tie for second at 8-8). The Dolphins led the AFC by allowing only 11 interceptions and 23 sacks on defense. Unfortunately, the Dolphins would lose their first playoff matchup that season, 27-20 to the Seattle Seahawks.
1984 was the season that new franchise quarterback Dan Marino would come into his own, setting several NFL single season passing records. Giesler would again start every game for Miami, as the team started out 11-0 before closing the season with an AFC best 14-2 record. The Dolphins led the NFL with 513 points scored, 6,936 yards of total offense, 6.5 yards per play, 387 first downs, 5,018 passing yards, and 49 passing touchdowns, while allowing an AFC fourth lowest 18 interceptions and an NFL fewest 14 sacks. Miami beat the Seahawks 31-10 and the Pittsburgh Steelers 45-28 on their way to Super Bowl XIX against the San Francisco 49ers, losing 38-16.
Giesler was limited by injuries to 13 starts in 1985, as Miami repeated as AFC East titleholders with a 12-4 record. Miami's passing offense ranked second to the Chargers in the NFL, with 4,114 yards and 31 touchdowns to their credit, allowing an NFL low 19 sacks. The Dolphins defeated the Cleveland Browns, 24-21 in the Divisional Playoff matchup before bowing out to the Patriots, 31-14 in the AFC Championship.
In 1986, Giesler again fought through injuries to make seven starts through the season, as Miami stumbled to an 8-8 record. The Dolphins still led the NFL with 430 points scored, 4,779 yards passing, and 46 touchdowns, allowing an NFL best 17 sacks against.
Giesler started nine of 13 games for Miami in 1987, as the team went 8-7 on the season (7-5 during non-replacement games). The Dolphins led the NFL with 3,876 passing yards and only 13 sacks given up all season.
In 1988, Giesler started nine of 13 games for the 6-10 Dolphins, as the team posted only the second losing record of Don Shula's then 19-year Dolphin's coaching career. Despite Miami's losing record, they still led the NFL with 4,516 passing yards, along with an incredible seven sacks allowed.