1)
Why were the Pelishtim subdued in the days of Shmuel?
1.
Radak: He went around Yisrael and rebuked them.
2.
Malbim: A Shofet or king must be a shield for Am Hashem both against the external enemy, and in conducting the nation itself - "u'Shfatanu Malkenu v'Yatza Lefaneinu v'Nilcham Es Milchamoseinu" (8:20). The Pelishtim were subdued by themselves and did not enter Yisrael's border by themselves, and when Yisrael entered Eretz Pelishtim, Hashem struck them in their land.
2)
Were the Pelishtim truly subdued all the days of Shmuel?
1.
Malbim: It was most of the days of Shmuel. Radak - in his old age he could not go around Yisrael to rebuke them.
