The former Republic of Ireland international made the observation during the opening minutes of the Premier League game between Manchester United and West Brom at Old Trafford on Saturday afternoon.
"He's a big lump, isn’t he, Salomon Rondon?” Lawrenson said on BBC Radio 5 live. “He’s a big old boy.”
Rondon started the game against United and played for 72 minutes, as the Baggies lost 2-0.
The Venezuela international took one shot, had a pass accuracy of 71%, attempted one dribble, won 33% of his headers, and made two interceptions, two clearances and two blocks.
The 26-year-old joined West Brom from Russian Premier League outfit Zenit Saint Petersburg in the summer transfer window.
Rondon has scored three goals and created seven chances in 11 Premier League appearances for the Baggies so far this season.
The former Malaga star has a pass accuracy of 63% and a shot accuracy of 45%, and has won 34 headers, two dribbles and four tackles.