Updated APR 05, 2015 9:10a ET  In the first four races of this 2015 season, Joe Gibbs Racing really had nothing to hang their hat on.  They weren't leading laps, winning races or even contending for wins.  That began to change three weeks ago at Fontana, where both Denny Hamlin and JGR teammate Matt Kenseth led a bunch of laps and had cars capable of winning. Unfortunately they both had issues and didn't seal the deal.  Then last week Hamlin not only won at Martinsville, but JGR also had three of their four teams finish in the top five. Kenseth finished fourth and David Ragan, the interim driver for JGR's No. 18 Toyota team while Kyle Busch recovers from injuries suffered in the season-opening XFINITY Series race at Daytona, came homein fifth.  It's still early in the season obviously but JGR is on of the few orgnizations whose teams I have seen show improvement. They realized early on that what they had when it came to the new rules package for 2015 wasn't making them competitive, so they went back to the drawing board and rectified the problem.  The problem was especially magnified after a poor showing by the JGR cars at Phoenix, which used to be one of their best tracks.  I think once they realized they need to make a change in what they were doing, it started paying dividends. By going back to work on aero balance and chassis combined with Toyota changing their engine combination, I believe they have found the right combination.  I've talked to a lot of drivers outside of JGR that tell me that JGR has definitely turned their program around. Let's face it, they struggled last year as an organization.  Think about poor Matt Kenseth. In 2013 he won seven races but then last year it was a goose egg. The only non-restrictor plate race they won in 2014 was at Fontana (where Kyle Busch won early on). Sure they won another 2014 race at Talladega when Hamlin took the checkered flag, but in the bigger picture that really doesn't mean all that much except naturally a win does get you into the Chase.  But running really well at Auto Club Speedway and then backing that up with a win at Martinsville last Sunday definitely makes a strong statement in the garage and to JGR's fans that the organization is back.  This coming weekend the race is at Texas Motor Speedway. That will be a really big test for the four JGR teams of drivers Hamlin, Kenseth, Carl Edwards and Ragan (until Busch returns). If they get back to where they were in 2013, then woe be onto the competition because they will be a major force to reckon with.  VIDEO: A look back at Denny Hamlin's winning weekend at Martinsville
Fomrer championship crew chief and current FOX Sports analyst Jeff Hammond says to watch out for Joe Gibbs Racing. Denny Hamlin's win at Martinsville could be a sign of bigger things to come.