World champion Casey Stoner endured a weekend to forget after being unable to show competitive pace for most of the grand prix following his commanding win in Qatar, the first race of the season.
Stoner finished the race down in 11th position while teammate Marco Melandri had to settle for 12th.
Last year, Jerez was one of only four tracks where Stoner did not make the podium, and Suppo admitted the team expected to have a difficult time.
"For sure our package here didn't work to perfection as it did in Qatar or in other track," Suppo told Italia1 television.
"We knew that: it was already our most difficult track for us last year, and the fifth place there was our worst except for Motegi and Sachsenring, but there were other problems there. So we knew we were playing defense here.
"(Technical director) Filippo (Preziosi) and the guys at home are always working to try to improve the bike. This year the bike has had an important improvement in the engine output, but it's obviously not enough on this track. However, both Casey and Marco appreciated this development.
"We'll carry on working. We know there are some track where the engine output doesn't give any problem and in fact gives some advantages, while some other where we struggle a bit more.
"But there are other tracks where other bikes struggle more than ours so it's normal."
Australian Stoner went off track twice during the race and Suppo reckons that only showed he is human following a dominant 2007 season.
"Stoner has demonstrated to be human," Suppo added. "Up to now he has always done incredible things, while today he made a mistake too. A shame, because despite the error, if he didn't make contact with Nakano he would have probably finished fifth. It was a racing incident, these things happen.
"However Casey in my opinion was very good and didn't give up. He carried on believing in it - maybe a bit too much in the first laps, but that's in a the character of the champions."
Suppo said he was not worried about the team depending exclusively on Stoner to get good results, after Melandri continued to struggle for pace.
"Honestly no. Marco has obviously started the season in a more difficult way than we had expected, but he has the talent and the grit to recover from it. Casey last year showed to be able to be ahead in almost every race, so I don't think we need to worry much."
autosport.com