One-time Storm hard-man Brett 'Bump' O'Farrell is the secret weapon behind the Eels' current defensive steel and the key man who has turned around one-time speed bump Mitch Moses.

‌The former Wests Tigers half joined the Eels mid-season and his recruitment has been more that timely given senior half Corey Norman was injured at the time Moses joined and key playmaker Clint Gutherson has since been rubbed out for the season with a knee injury.

The Eels have won seven from nine games since Moses joined and while there were never any questions over his boundless talent, fans have been buoyed by the steep improvement in his once-leaky defence.

In 10 games for Wests Tigers this year, Moses missed 49 tackles at 4.9 per game, in a team leaking 25.4 points per game. In the Eels system under 'Bump', Moses missed 20 tackles in his first four games at five per game (on par with his Tigers form) before the improvement really took hold.

In the past five rounds Moses has missed just 13 tackles at 2.6 per game in team conceding just 58 points at 11.6 per game; crucially, the Eels have won all five of those games to move to sixth on the ladder. 

For comparison, looking at other halves who are regarded as solid defenders in their past five games, Nathan Cleary and Kieran Foran (both 11 misses at 2.2 per game), Daly Cherry-Evans (16 at 3.2 per game), Michael Morgan (17 at 3.4 per game) and Mitchell Pearce (18 at 3.6 per game) have all missed similar or greater numbers of tackles than Moses.

Eels back-rower Tepai Moeroa – a noted defender who spends much of his time on field helping out Moses on the Eels right edge – praised the improvement in Moses's defensive work since he joined Parramatta.

"Before he came to Parra he wasn't known for his defensive abilities but now he makes his one-on-one tackles and even puts on a couple of shots now and again," Moeroa smiled at Eels training on Monday.

"He's brave, he's not afraid of the contact."

Moeroa spoke of the Eels "contact room" where "contact technician" O'Farrell – who played 20 games for Melbourne from 1999 to 2001 – hardens up the players ready for battle.

"We've got our contact technician 'Bump'. He's been working one-on-one with [Moses]. Tackle technique, wrestle and stuff like that," Moeroa said.

"It's more technique, teaching him how to tackle properly and build his confidence.

"I guess he's just been working hard on his defence in our contact room. He's not afraid to put a couple of shots on in there so I guess it's taking that confidence out on the field."

Moses recently told NRL.com about the work he had done one-on-one with the man they call 'Bump', who is in his second year of doing a few sessions a week at Parramatta along, with working across several other clubs and football codes.

"I've been working pretty close with our tackle tech coach 'Bump'. He's been massive for me, always gets me in before training to do a few extra tackles," Moses said after the 13-12 win over the Bulldogs a month ago.

"I felt pretty comfortable. It was just about me getting more comfortable week by week, new defensive structures, getting used to what Parra do and I'm definitely feeling more comfortable now."