WHEN Adelaide acquired ex-Carlton recruit Sam Jacobs in last year's exchange period, some of the Crows faithful questioned why, given the introduction of the new substitute rule, the club would pursue another ruckman.

Jon Griffin had requested a trade to Western Australia for family reasons, but the Crows still had regular No.1 ruckman Ivan Maric, injury-plagued utility Brad Moran, promising tall Shaun McKernan and the untried James Craig to call upon.

Maric had been a mainstay in the team for the previous three seasons, using his strength and passion to provide a solid contest in the ruck, but it didn’t take long for Jacobs to assume the mantle as Adelaide's preferred ruckman.

Jacobs has played 12 straight games since returning from a pre-season hamstring injury against his former club in round four, resigning Maric to the SANFL.

At 203cm, he's slightly taller than Maric (200cm) and has enormous reach, ranking fourth in the AFL for hit-outs despite having missed the three games through injury.

He's also mobile enough to get involved in general play, as evidenced by his performance in the first half against Essendon at AAMI Stadium on Friday night.

Jacobs and defender Graham Johncock, who injured his hip early in the second term, were the two most influential players on the ground in the first quarter.

Jacobs, whose form had been steadily building with solid displays against Geelong and the Sydney Swans in the last fortnight, amassed seven possessions and six hit-outs (one more than the Essendon's team total for the quarter) to eclipse David Hille and resting forward Paddy Ryder in the ruck.

By half-time, the former Woodville-West Torrens junior had collected 10 disposals and 15 hit-outs, and was on track for a career-best return.

He'd also taken a game-high four contested marks, monstering every high ball that came his way to help Adelaide dominate the statistic 17-6 at the main break.

"My marking is something I've worked on, so it was nice to hold onto a couple early," Jacobs said after the game.

Unfortunately, Jacobs' performance in the second half mirrored his team's performance.

The emerging 23-year-old suffered a knock to his lower leg early in the third quarter.

He was able to play out the game, but struggled to shake the injury and only managed five possessions in the second half.

"I'm not sure what I've done [to my leg]," he said.

"I'll have some scans [Saturday], but hopefully it's nothing serious."

The Bombers eventually gained control at the stoppages, winning the clearances 15-5 in the final quarter and staging a 47-point turnaround after half-time to run out 11-point winners.

"We had a great start and that was super, but we lost our way a bit probably late in the third quarter and in the last quarter as well," he said.

"We were still up by 16 points at the last change, so it was very disappointing to lose like we did.

"They kicked some pretty big goals in the third quarter and we couldn’t stop their run by nailing our opportunities.

"We were a couple of guys down, but that's no excuse because we still had chances to win it and we didn't."

Katrina Gill covers Adelaide news for afl.com.au. Follow her on Twitter: @AFL_KatrinaGill