MIAMI (CBSMiami) – The Miami Dolphins have struggled to put a winning team on the field in recent years and 2013 is no different. The Fins have problems across the field with rookies, but the veteran struggles continue a growing and troubling trend for the Fins.

The Dolphins have signed a multitude of free agents the last few seasons, and let multiple veterans leave South Florida. One thing has been constant throughout though, when veterans come to Miami their skills go down and when they leave; typically they have a career renaissance.

CBS4 news partner the Miami Herald first pointed out the trend looking at Brandon Marshall, who averages around 20 more catches a season when he’s not in Miami; Philadelphia’s Evan Mathis who was cut by Miami and now ranked the top guard by Pro Football Focus; to Reggie Bush who is tearing it up in Detroit.

Former cornerbacks Sean Smith and Vontae Davis left or were traded and both are ranked in the top 12 cornerbacks in the league. According to the Herald, Smith has surrendered a quarterback rating of 58.2 in his coverage area this year.

Even Jake Long, who some Fins fans considered to be too injury prone to keep, has drastically improved his overall game since leaving Miami and heading to St. Louis, according to the Herald.

Looking at the Dolphins’ free agent additions this year paints a similar picture of players coming to Miami and watching their production decline. Right tackle Tyson Clabo was a star in Atlanta giving up just five sacks last year, but has become a turnstile benchwarmer after giving up eight sacks in six games.

Richard Marshall was brought in last season and suffered an injury a few games into the season and was cut before the 2013 season began. The Fins spent a truckload of money on linebackers Philip Wheeler and Dannell Ellerbe, but neither has excelled, especially in pass coverage.

Wheeler has been especially poor in pass coverage, allowing opposing quarterbacks to post a quarterback rating of 121 when they throw at him. Neither have helped the pass rush and both will cost the franchise much more in the long run than Karlos Dansby and Kevin Burnett.

Mike Wallace was brought in with a huge contract in the offseason and expected to make an immediate impact by stretching the field with his speed and route running. He’s been targeted 64 times this season and caught just 30 passes for 398 yards and just one touchdown.

He hasn’t lived up to his huge contract and his payday jumps to $17 million next season which could cause salary cap issues for the Fins.

The Fins’ did strike gold on Brandon Gibson, who was playing well until suffering a season-ending knee injury. Miami also hit gold on cornerback Brent Grimes, who is on a one-year contract.

But, with Miami sinking fast again this season, and with players showing little to no improvement on the roster; there’s discontent among the fan base and the Fins have to right the ship in a hurry. With the Heat starting Tuesday and UM and FSU playing well, the Fins could see fans abandon the team if they start to sink in the second-half of the season.

(TM and © Copyright 2013 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2013 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Miami Herald contributed to this report.)