The recent departing of Timo Glock, though not a sacking has made me think of some of the harshest or most unfair dismissals I've known or heard of. Here are some I can think of. Please feel free to add some good ones to mine - they can include all of motorsport!

MARTIN BRUNDLE - BENETTON, 1992
Retired from first 4 races, but recovered to score almost 40pts - just 18 off 2nd in WDC! Scored several podiums and outraced Schumacher on more than a few occasions. Never outqualified him though. Was dropped for Patrese who wasn't really any quicker in 1993 and scored only 20pts.

PEDRO DE LA ROSA - ARROWS, 2001
Pedro had been a revelation in the fast 2000 Arrows with the best ever livery challenging for several podiums. He was given a contract to stay at Arrows when he had offers from team like BAR. Only for the team to go back on it before the start of 2001, leaving Pedro out in the cold as the other seats were now filled.

HEIKKI KOVALAINEN - CATERHAM, 2013
Carried the Caterham team for 3 years, only to be basically told that HE should have been more grateful by Mike Gascoyne.

JARNO TRULLI - RENAULT, 2004
Okay I'm not holding back on this one - here goes: Jarno had been basically outperforming Fernando Alonso in 2004 against expectations. This came to a head in Monaco when Trulli won while Alonso crashed. All Flavio could hiss was "This changes nothing"! Trulli was 16pts ahead in the WDC as well as the quicker qualifier. The problem was that Alonso, like in 2007, wasn't too happy being beaten. Therefore, neither was his manager Flav. From that point on, Trulli's season mysteriously fell apart and he was ousted after Monza. Conversely, Alonso's performances perked up.