Arteta needs new defence to take Arsenal forward - what's Lampard's excuse?
After 95 enthralling minutes at Stamford Bridge, Chelsea and Arsenal were left to share the spoils: two goals and one point apiece, and clear problems to solve over the remainder of the season.
For the neutrals, this was a fabulous encounter, a heady blend of slapstick errors, fine finishes and furious endeavour creating a brilliant advert for the quality of the Premier League product, if not necessarily the teams themselves.
For all their faults, you cannot accuse Chelsea or Arsenal of being boring. But the faults are there. The worry is how Frank Lampard or Mikel Arteta go about fixing them to keep their respective seasons meaningful.
On the evidence of Tuesday's comeback, Arteta has got Arsenal fighting in a way not seen for some years in north London, but the state of their defence means any hope of finishing in the top four remains forlorn. For Lampard, the excuses are not so clear.
After the loss to Newcastle United, Lampard blamed a lack of goalscorers for not putting the visitors out of sight at St James' Park before Isaac Hayden's stoppage-time slap in the face.
"We know we have problems at the top of the pitch in terms of we don't get enough goals," he said. "If you don't score, you are always liable for a sucker punch, and they got it.
"We can't work any more in training on finishing. You need to have that killer instinct in front of goal. We need to score more goals from front-line areas if we are going to get to where we want to be."
It's true they could have been more ruthless against the Gunners. Tammy Abraham sent two headers into Bernd Leno's hands and Michy Batshuayi made a mess of a late chance.
Given Arsenal scored from their only two shots of the match, you could understand Lampard if he rails against his side for not killing off a team who played a man light after David Luiz forever ingrained himself in Chelsea folklore by getting sent off 26 minutes into his latest return.
Goalscoring looked artfully simplistic for Lampard the Chelsea player, but his concerns as their coach are more complex.
Gabriel Martinelli's equaliser came straight from a Chelsea corner and a slip by N'Golo Kante, a sequence of buffoonery only overshadowed by Shkodran Mustafi, Leno and David Luiz earlier turning an errant backpass into a circus act.
Hector Bellerin's leveller, three minutes after Cesar Azpilicueta looked to have won the game, was the result of Chelsea failing to play a spot of keep-ball against 10 tiring opponents. These are passages of play that a top side should know how to navigate.
Suggesting Lampard's job should be under threat would be nonsense, but the fact remains Chelsea have lost six matches and won only four in the Premier League since beating Crystal Palace in mid-November.
He has faced nowhere near the lambasting of Manchester United and Ole Gunnar Solskjaer, despite Chelsea losing more matches this term. Beat Burnley on Wednesday and the Red Devils will be just three points behind fourth-place Chelsea in the table.
Arteta has evidently impacted both Arsenal's mental fortitude and a previously alienated fan base, and this was a stirring performance in the circumstances, but there is little more to expect from a team with a defence such as theirs. They are still 10 points off the top four and only seven above the bottom three, which is a frank but fair reflection of their quality at the back.
With their transfer ban over (not even that is a wholly satisfying excuse – they knew they had £58million winger Christian Pulisic to bring into the side even during the previous window), Chelsea will almost certainly be exploring the market in the next 10 days. Edinson Cavani would be a worthwhile addition to bring those killer goals Lampard craves, and alternatives will surely be pursued.
Arsenal are also expected to make signings, with Jerome Boateng tipped to bolster the defence. Whether the Bayern Munich centre-back is still of the required calibre remains to be seen, but you can certainly imagine Arsenal's results improving quickly under Arteta once top-class defenders are in place, be that in January or at the end of the season.
How Chelsea kick on under Lampard is harder to answer.