Abraham and Timo Werner discussed who should take a penalty before Chelsea captain Azpilicueta intervened in a briefly heated debate.
During the 2019-20 campaign, Mount played 51 matches and it was more than any other player in the squad.
Lampard's remarks came after Chelsea's penalty-shootout loss against Tottenham in the Carabao Cup last-16 match on Tuesday.
He said it was difficult to put in enough work on the training ground, with two matches a week and a looming international break.
Christian Pulisic, Tammy Abraham, Mason Mount, Fikayo Tomori, and Emerson Palmieri were required to self-isolate amid the COVID-19 pandemic during the pre-season, Goal.com reported.
Recently, Chelsea suffered a 2-1 defeat at the hands of Arsenal in the FA Cup final.
Arsenal, however, hold the record for most FA Cup wins as they have lifted the title a record 13 times.
On Sunday, Chelsea defeated Wolves 2-0 while Manchester United secured 2-0 win over Leicester City in their final clash of the season.
Chelsea were hit with a transfer ban prior to the season and they had to be content with playing talented youngsters from the academy who repaid Lampard's faith.
Chelsea will be facing Liverpool later today in the Premier League and the side would be looking to cement their place in the top four to gain qualification for the Champions League.
Frank Lampard stopped short of being critical of the VAR decisions that have gone Manchester United's way in recent matches.
Victory opens up a four-point lead for third-placed Chelsea over Leicester and Manchester United, who both have a game in hand later this week.
Chelsea secured a 1-0 win over Norwich City in the ongoing Premier League here on Wednesday.
Christian Pulisic has talent to score goals like Salah, Mane or Sterling, says Chelsea manager Frank Lampard
The 21-year-old United States international is now Chelsea's second top scorer in the league with seven goals.
Lampard helped Chelsea to the fourth spot in the Premier League before the season was abruptly halted in March due to coronavirus pandemic.