David Garrard has been an average quarterback through the Jaguars first six games. He was terrible in the first two (losses against Indy and Arizona), good in the next two (wins against Houston and Tennessee), and mediocre at best against Seattle and St. Louis.
Garrard has solid stats, but has shown that he's nothing more than mediocre throughout the first six games. He's beaten up on some of the worst passing defenses in the league, and has looked lost against better competition.
Running backs: B+
Maurice Jones-Drew has been very good when he's had the opportunity to touch the ball. MJD leads the NFL in rushing touchdowns, and there seems to be little doubt he can handle the full load as an every downs running back. Greg Jones has been a solid blocker, but hasn't been involved much with the football. Rashad Jennings hasn't been overly impressive in limited work.
Wide receivers/tight ends: B-
The Jaguars pass catchers are somewhat limited by the quarterback, as rarely the ball will hit them in stride. This hampers them from making much YAC, and the receivers get labeled as slow or nonexplosive. There have been very few drops this season, and the emergence of Mike Sims-Walker has been a godsend. Torry Holt is playing the role as possession receiver and he's done a very nice job. Marcedes Lewis is quietly having a great year, and he catches every ball that he doesn't have to leap for or is beneath his knees. Mike Thomas adds an element of suddenness, and should be a bigger part of the offense as the season progresses.
Offensive line: C
The Jaguars offensive line struggled mightily in the season opener with pass protection, and have since improved. When teams have lined up against them with the usual seven in the box, they've been able to pave the way for Maurice Jones-Drew and the running game. Eugene Monroe is learning on the job, and he's improving from week to week. Tra Thomas is a more than capable backup, who may be better than Monroe at this point in his career. Eben Britton has been somewhat up and down, but he's been good enough to keep his job. Uche Nwaneri is taking strides at right guard, and Vince Manuwai has played well at left guard with the exception of the Seattle game. Brad Meester has been average.